chapter 4: properties of elements and compounds · chapter 4: properties of elements and compounds...

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Chapter 4: Properties of Elements and Compounds

Objectives

In this chapter, you will:

• identify elements and compounds

• describe important physical and chemical properties of elements

• explain how properties of elements and compounds determine their practical uses

• investigate the physical and chemical properties of elements

• conduct tests to identify common gases based on their chemical properties

4.1 Studying Matter

What is matter?

Matter is anything that has ______________ and ____________________________

Examples: book, desk, air, YOU, etc.

Matter is ______________ ______________ (eg. fire)

Classification of Matter

Scientists group materials

Based on ______________ ______________

One way is based on Particle Theory of Matter

The Particle Theory of Matter


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Classification of Matter

based on Particle Theory of Matter

1. Pure Substance

Contains only __________________________________________

Can be further classified into:

o ______________

o ______________

1a. Element

A ______________ substance

Cannot be _________________________ further by chemical or physical methods

1b. Compound

A ______________ substance

Made of two or more different elements that are ____________________________

Can be broken down into its ______________ only by chemical methods

2. Mixture

Matter that contains more than one kind of particle

______________ combined

______________ combined

Can be separated by ______________ methods


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Separating Mixtures

______________: - separates solids from liquids or gases

______________: - Separates liquids in a mixture ; Based on boiling point

______________: - Separates iron and steel objects from other objects

Chemistry, Society and the Environment

Elements and compounds have many positive effects on society

Production of ______________ and ______________

Improvement in ______________ yields

Increased ______________ of available products

Use of elements and compounds can also result in negative consequences

______________ released into the atmosphere and waterways

______________ of toxic chemicals in soil and on food products

Direct exposure of ______________ chemicals to humans

4.2 Physical Properties

Physical Properties

Characteristic of a substance

Can be observed and measured without changing the identity of the substance

Two types :

1._________________

2. _________________


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1. Qualitative Physical Properties

Can be observed and described without detailed measurement

Property Examples

colourless, red, black

sweet, pungent, mouldy

solid, liquid, gas

rough, smooth, bumpy

shiny, dull

soft, pliable, hard

2. Quantitative Physical Properties

Can be measured and assigned a particular value

Property Description

resistance to flow

temperature of melting

temperature of boiling

ability to dissolve in another substance

ability to scratch another material

ability to conduct electricity or heat

ratio of mass to volume

Physical Properties

states of matter

melting and boiling points

solubility

hardness

conductivity

density


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States of Matter

A qualitative physical property

1. ______________

2. ______________

3. ______________

Melting and Boiling Points

A ______________ physical property

______________ point is the temperature at which a solid turns into a liquid

______________ point is the temperature at which a liquid turns into a gas

Solubility


Measures the ability of a substance to ______________ in another substance

The maximum quantity of a substance that can dissolve in a given amount of solvent

at a particular ______________ and ______________

Example: sodium chloride (table salt)

39.5 g/100 mL in water at 25 °C and atmospheric pressure


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______________ solution is a solution with water as a solvent

______________ means does not dissolve or has a very low solubility

Examples: copper in water

Fat can be a ______________

Some chemicals dissolve in fats

eg. DDT (dichloro-diphenyl-trichloroethane)

a synthetic pesticide

bioaccumulates and biomagnifies in mammals

Hardness


Ability to ______________ another material

Between 1 to 10 on the Mohs scale

Fingernail --- 2

Diamond --- 10 (the hardest natural material)

Conductivity


Ability to conduct ______________ or he______________ at

Copper: conducts electric current very well

Aluminum: conducts heat very well

Density


The ratio of the ______________ of a substance to the ______________ it occupies

o Oil ______________ on water

o Iron nails ______________ in water

o A cruise ship ______________ on the sea water


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Water’s Unique Physical Properties

All ______________ ______________ exists on Earth

______________ ______________

Can absorb a lot of ______________ before it gets hot

Its solid form is ______________ ______________ than its liquid form (ice acts as an

insulator for water below)

Density - Calculation

Density =

mass

volume

D =

m

V

Unit for density is ______________

Sample Problem

A sample of silver has a mass of 5.04 g and a volume of 0.480 cm3. What is the density of

silver?


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4.3 Chemical Properties

Chemical Properties

Ability of a substance to ______________ (change)

Forms ____________________________

Example:

glow stick produces light when chemicals combine

chemiluminescence

Reactivity with Other Substance --- Water

calcium carbide + water

o acetylene gas

o Combustible

o Generates light

Reactivity with Other Substance --- Oxygen

aluminum + oxygen

o aluminum oxide

o protects metal from weathering

Reactivity with Other Substance --- Acids

baking soda + acid

o carbon dioxide gas

o help batter and dough rise

Reactivity with Other Substance --- Another Pure Substance

Knowing how pure substances react with each other

o enable chemists to develop new products

eg. Peroxide change melanin to colourless

--> Used as hair dyes


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Combustibility

Ability to ____________________________

eg. Propane heats the air in hot-air balloons

Stability

Ability to ____________________________

not break down or decompose easily

Useful chemicals must have enough stability to exist long enough to carry out its

required function

Toxicity

Ability to ____________________________ in plants and animals

Reported as a ______________________ (dose required to kill 50% of the exposed

population)

eg. Clostricium tetani

______________ has to be considered too (eg. DDT)

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5.1 Evolution of the Atomic Model

Early Greek Theories

400 B.C. - Democritus thought matter could not be _________ __________.

This led to the idea of __________ in a void.

350 B.C - Aristotle modified an earlier theory that matter was made of four “elements”:

__________, __________, __________, __________.

Aristotle was wrong. However, his theory persisted for 2000 years.

John Dalton

1800 -Dalton proposed a modern atomic model based on _____________ not on pure reason.

• All matter is made of _____________.

• Atoms cannot be _____________, _____________or _____________into smaller particles.

• Atoms of an element are _____________.

• Different elements have _____________atoms.

• Atoms of different elements combine in constant ratios to form _____________.

• Atoms are _____________ in reactions.

His ideas account for:

1) The Law of ____________________of Mass: atoms are neither created nor destroyed

2) The Law of ______________Composition: elements combine in fixed ratios

Adding Electrons to the Model

• Materials, when rubbed, can develop a __________difference.

• This electricity is called “____________” when passed through an evacuated tube.

These rays have a ________ _______and are ___________.

• Thompson noted that these ________ ____________ particles were a fundamental part of all

________.

Adding Electrons to the Model

1) Dalton’s “Billiard ball” model (1800-1900): Atoms are ___________and _____________.

2) Thompson “Raisin Bun” model (1900): ___________electrons in a _________framework.

3) The Rutherford model (around 1910): Atoms are mostly __________ ___________.

Negative _________ orbit a positive __________.


Ernest Rutherford

Rutherford shot _____________ () particles at gold foil.

Most particles passed through. So, atoms are mostly ______________.

Some positive -particles deflected or bounced back!

Thus, a “nucleus” is ______________.& holds most of an atom’s ______________..

If Rutherford’s model is correct, why don’t the negatively charged electrons spiral into the

positive nucleus and collide with it?

Bohr’s model

Electrons can only move within ______ regions (_______ ______or ________)

An electron can be bumped up to a higher shell if it absorbs a specific amount of _________

(_________)

Eg. hit by an electron or a photon of light.

Bohr-Rutherford Model

A central positive ___________

____________in energy levels around the nucleus

5.2 The Structure of the Atom

An Atom

The ______________ particle of an element that retains the ______________of the element

Consists of ______________orbiting around the _______________

_____________ : a negatively charged particle within the atom

_____________ : the positively charged centre of an atom


Nucleus

Made up of _____________and _____________

_____________ : a positively charged particle that is part of every atomic nucleus

_____________ : an uncharged (neutral) particle that is part of almost every atomic nucleus

Structure of An Atom:

Name Relative Mass Electric Charge Location in the Atom

proton

neutron

electron

Atomic numbers, Mass numbers

Elements are often symbolized with their __________________ and _____________________

These values are given on the ______________ table.

For now, round the mass # to a whole number.

These numbers tell you a lot about atoms.

Atomic numbers, Mass numbers

atomic number =

=

mass number =

SO… # of protons =

# of electrons =

# of neutrons =


Calculate # of protons (p+), neutrons (n0), and electrons (e–) for Ca, Ar, and Br.

Atomic Mass p+ n0 e-

Ca

Ar

Br

Bohr - Rutherford diagrams

1. Find : # p+ , # e- and # n0

2. Draw nucleus in circle: # p+ and # n0

3. Draw electrons around in shells: 2, 8, 8

Draw He and Li:

Draw Be, B, and Al:


Isotopes

Atoms of the same element that have different numbers of ___________are called isotopes.

Isotopes can be written with the name followed by the ______________________ : ________

Due to isotopes, atomic masses are not round numbers.

Li (atomic mass = 6.9) is made up of both 6Li and 7Li.

Sometimes an isotope is written without its atomic number - e.g. 35S (or S-35). Why?

Answer-

Draw B-R diagrams for the two Li isotopes.

5.3 Periodic Table of Elements

Mendeleev

In 1869, Dmitri Ivanovitch Mendeléev created the first accepted version of the

___________________.

He grouped elements according to their __________________.

Atomic mass is the __________________ of the naturally occurring __________ of an element.

As he did, he found that the families had similar _____________________________.

______________________ were left open to add the new elements he predicted would occur.

Modern Periodic Table

However, there were a few elements that Mendeleev had to put out of order to fit similar

properties.

Today’s periodic table is arranged by increasing ______________________(# of __________)


Periodic Table

The periodic table __________ the elements in a particular way. A great deal of information

about an element can be gathered from its __________ in the period table.

For example, you can predict with reasonably good accuracy the __________ and __________

properties of the element. You can also predict what other elements a particular element will

__________ with chemically.

Understanding the organization and plan of the periodic table will help you obtain basic

information about each of the 118 known _____________.

Key to the Periodic Table

Elements are organized on the table according to their ____________________, usually found

near the top of the square.

The atomic number refers to how many __________ an atom of that element has.

For instance, hydrogen has ____ proton, so it’s atomic number is ____.

The ____________________ is unique to that element. No two elements have the

__________ atomic number.

What’s in a square?

Different periodic tables can include various bits of information, but usually:

atomic number

symbol

atomic mass

number of valence electrons

state of matter at room temperature

Valence Electrons

Valence electrons are the electrons in the __________ occupied ____________________ of

an atom.

These are the electrons that are transferred or shared when atoms bond together.

Chemical Symbols

All elements have their own unique ____________________.

It can consist of a single ____________________ letter, or a _______________letter and one

_______________ case letter.


Some common Chemical Symbols:

Element Symbol Origin of name

aluminum Latin: alumen, a bitter salt

fluorine Latin: fluor, a flow

carbon Latin: carbo, charcoal

potassium Latin: kalium

sodium Latin: natrium

tin Latin stannum

helium Greek: helios, Sun

chlorine Greek: chloros, pale green

neon Greek: neos, new

uranium named after planet Uranus

magnesium Named after a district in western Turkey

3 Main Groups

1. ________________ : left side

2. ________________ : right side

3. ________________ : staircase near the right

have properties of both ________________ and ________________

Properties of Metals

All metals appear on the ____________ side of the periodic table

Metals are good conductors of ____________ and _______________.

Metals are ____________.

Metals are ______________(can be stretched into thin wires).

Metals are ________________(can be pounded into thin sheets).

A chemical property of metal is its reaction with water which results in _________________.


Properties of Non-Metals

All non-metals (except hydrogen) appear on the ____________ side of the periodic table

Non-metals are ___________ conductors of heat and electricity.

Non-metals are ___________ ductile or malleable.

Solid non-metals are ____________ and ____________ easily.

They are ____________.

Many non-metals are ____________.

Properties of Metalloids

Metalloids form a ______________ line toward the ____________ side of the periodic table

Metalloids (metal-like) have properties of both ____________ and ________________.

They are solids that can be shiny or dull.

They conduct heat and electricity better than non-metals but not as well as metals.

They are ductile and malleable.

Mining for Metals

Some elements are ______________ metals that are easy to shape and found in nature

However, mining causes serious social and environmental impacts

_______________________

_______________________

Use cyanide-based chemical to extract gold

______________ substance for human and wildlife

Solution: buy recycled or vintage gold jewellery or use ______________materials

Metals and Health

Metals are also part of essential processes in plants and animals

_____________ in blood for _____________ transport

___________, ___________, ___________, ___________are also important

However, metals at too high a level can be ______________

Too much iron can damage the ___________and ____________

Certain metals can __________________and ___________ (aluminum, lead, mercury)


Mercury Pollution

Some mercury occurs naturally but most results from ____________________________ (eg.

burning waste materials and fossil fuels)

Bacteria convert elemental mercury to ____________________________which can then be

taken up by animals

These bacteria are most active in ______________ environments thus ________________ are

a key source of mercury poisoning

Contaminates ________________________ and ____________ in lakes and rivers (both

______________and ______________)

Causes severe ________________ in many people

Families

___________________of elements are called groups or families.

Elements in each family have ______________but not identical properties.

For example, lithium (Li), sodium (Na), potassium (K), and other members of ______________

are all soft, white, shiny metals.

All elements in a family have the same number of ______________________.

Periods

Each _____________________ of elements is called a period.

The elements in a period are ______________________ in properties.

In fact, the properties change greatly across even given row.

The first element in a period is always an extremely ______________ solid. The last element in

a period, is always an ______________ gas.


Hydrogen

The hydrogen square sits atop Family 1, but it is not a member of that family. Hydrogen is in a

class _____________.

It is a ________at room temperature.

It has ________proton and ________ electron in its one and only ___________.

Hydrogen only needs ________electrons to fill up its valence shell.

Alkali Metals

The alkali family is found in the ________ column of the periodic table.

Atoms of the alkali metals have a ________ electron in their outermost level, in other words,

________ valence electron.

They are ________, have the consistency of _______, and are easily cut with a knife.

They are the ________________metals.

They react violently with ________.

Alkali metals are never found as free elements in nature. They are always bonded with another

element.

Alkaline Earth Metals

They are never found uncombined in nature.

They have ________valence electrons.

Alkaline earth metals include magnesium and calcium, among others.

Transition Metals

These are the metals you are probably most familiar: copper, tin, zinc, iron, nickel, gold, and

silver.

They are ________________of heat and electricity.

The compounds of transition metals are usually brightly ________ and are often used to color

paints.

Transition elements have ________ valence electrons, which they lose when they form bonds

with other atoms.

Transition elements have properties similar to one another and to other metals, but their

properties do not fit in with those of any other family.


Halogen Family

The elements in this family are fluorine, chlorine, bromine, iodine, and astatine.

Halogens have ________ valence electrons, which explains why they are the

________________ non-metals. They are never found free in nature.

Halogen atoms only need to gain ____ electron to fill their outermost energy level.

They react with ________ ________ to form salts.

Noble Gases

Noble Gases are ________ gases that are extremely _____________

One important property of the noble gases is their inactivity. They are inactive because their

outermost energy level is ______.

Because they do not readily combine with other elements to form compounds, the noble gases

are called ________.

The family of noble gases includes helium, neon, argon, krypton, xenon, and radon.

All the noble gases are found in small amounts in the earth's atmosphere.

Rare Earth Elements

The thirty rare earth elements are composed of the lanthanide and actinide series.

Many of them are ________ or man-made.

5.4 Trends in the Periodic Table

Valence Electrons

Valence electrons are the electrons in the ________________ occupied energy level of an

atom.

Many ________________ are determined by the arrangements of the valence electrons.

Elements in the same group has the ________________ number of valence electrons, thus

react in a ________________ way


What does it mean to be reactive?

We will be describing elements according to their reactivity.

Elements that are reactive bond __________ with other elements to make __________.

Some elements are only found in nature bonded with other elements.

What makes an element reactive?

An __________ valence electron level.

Rule of __________ : All atoms (except hydrogen) want to have _____ electrons in their

very outermost energy level

Atoms bond until this __________ level is complete. Atoms with few valence electrons

__________ them during bonding. Atoms with 6, 7, or 8 valence electrons __________

electrons during bonding.

Families

The _______________(Group 1) are the most reactive metals

need to lose only _____ electron

The __________(Group 17) are the most reactive non-metals

need to gain only _____ electron

Noble Gases (Group 18) are non-reactive

Outermost shell already __________

Atom Size (Metals & Non-metals)

Atomic size increases when

1. Going __________ a group (higher energy level)

2. Going across a period from ____________________ (same energy level but less

protons)


Metal Reactivity and Atom Size

When the valence electron is farther from the nucleus

can be lost more __________

more __________

NOTE

Different reactivity trend for non-metals!!!

You will learn that in Chemistry 11

Which metal is more reactive?

1. Potassium or Rubidium?

2. Magnesium or Beryllium?

3. Potassium or Calcium?

4. Cesium or Strontium?



Chapter 6: Understanding the Properties of Compounds

Objectives

In this chapter, you will:

• explain the difference between ionic compounds and molecular compounds

• demonstrate an understanding of the important properties of ionic and

molecular compounds

• assess the social, environmental, and economic impacts of the use of some

common compounds

6.1 Ionic Compounds

Forming Ions

________________ : a positively or negatively charged atom or molecule

Metal ________________ electron(s) --> ________________ ion

Nonmetal ________________ electron(s) --> ________________ ion

Atomic

number

Mass

number

p+ n e-

Mg2+

O2-

Al3+



Ionic Compound

________________ + ________________

electron(s) ________________ from metal to nonmetal

made of oppositely charged ________________

ions held by ________________ ________________ (+ attracts -)

Chemical bond: a chemical link between ________________

Ionic bond: a chemical bond between ________________________________

Properties of Ionic Compounds

Ionic bonds are ________________________________

Results in the following properties:

o Solids

o High melting points

o Soluble in water

o Good conductors of electricity

Sodium Fluoride

An ionic compound ________________ and ________________

PRO:

o In ________________ to strengthen tooth enamel and reduce cavities

o Fluoride is added to ________________ ________________ in Canada

CON:

o Too much can cause cancer, fragile bones and improper brain development in

________________

o Recent debate over the optimal level of human exposure



Plant Fertilizers

PRO:

o Soluble ionic compounds to provide ________________

CON:

o Easily washed away from fields and end up in waterways

o --> negative effects on ________________

Road Salt (sodium chloride)

PRO:

o ________________ freezing point of water --> ________________

o Saltwater mixture improves ________________

o Easier snow removal

CON:

o Attracts ________________ --> hazardous for animals and drivers

o Increased ________________ --> increased ________________



How to name Ionic Compounds

1.Name the 1st element (metal)

2.Name the 2nd element (non-metal) with suffix –ide

Chemical Formula Chemical name

NaCl

K2O

AlF3

How to write Chemical Formula for Ionic Compounds

1.Write symbol for 1st element (metal)

2.Write symbol for 2nd element (non-metal)

3.Determine number of atoms for each element using combining capacity or ion charges

Chemical Name Chemical Formula

potassium bromide

magnesium chloride

sodium oxide

6.2 Molecular Compounds

2 types of compounds

1.Ionic compound:

a compound made of oppositely charged ions

2.Molecular compound:

a compound formed when atoms of two or more different elements

________________ electrons

Molecular compounds

When atoms share a pair of electrons to form full outer energy levels

form a ________________ ________________

form a ________________ ________________



Molecular compounds

Composed of 2 or more ________________

Smallest discrete particle of a pure substance, which has one ore more shared pairs

of electrons ---> a ________________

Also called ________________ compounds

3D Water Molecule Model Bohr-Rutherford Water Molecule

Diatomic molecule

Composed of 2 atoms of the ________________________________

Covalently bonded

7 diatomic molecules:

1.

2.

3.

4.

5.

6.

7.



Properties of Molecular Compound

Covalent bonds are very ________________

BUT attraction between molecules is ________________

leads to the following properties:

Made up of non-metals elements

________________ ________________ of heat and electricity

________________ melting points

________________ boiling points

Soft

Not very soluble in water

Plastics

Made of giant molecular compounds called ________________

Many ethylene molecules joined together to make this class of plastics called

polyethylenes

Number of ethylene molecules and their density determines the type of plastics:

o Shopping bags

o Toys

o Bottles/containers

CON:

________________________________ easily

Chemicals can ________________ ________________ in landfills

Discarded plastics hazardous to ________________

Compounds Ionic compounds Molecular compounds



How to Name Molecular Compounds

1.Name the first element

2.Name the second element using the suffix –ide

3.Use prefix to represent the number of atoms of each element

4.Check for exceptions:

1.The prefix mono- is not used for the first element

2.When mono- is followed by oxide, use only one “o” monoxide

Memorize this table!

Chemical Formula Chemical Name

S2F6

N2O5

NO

P3Cl7

How to Write Chemical Formula for Molecular Compounds

1.Write symbol for 1st element

2.Write symbol for 2nd element

3.Determine number of atoms for each element from the prefixes

Chemical Name Chemical Formula

dinitrogen tetraoxide

carbon disulfide

dihydrogen monoxide



6.3 MODELLING COMPOUNDS

MODELLING COMPOUNDS

better perspective on the ________________ and ________________ of a structure

2-D MODELS

simplest model (Bohr-Rutherford models)

can be drawn on ________________

show ________________ compounds form

When two atoms share two pairs of electrons, a ________________ ________________ is

formed, as illustrated below.

The structure of carbon dioxide

3-D MODELS

show ________________ ________________ between atoms in a compound

use modelling kits or computers

________________ of a molecule important to ________________ of the compound

Examples:

1. BALL-AND-STICK MODELS

2. SPACE-FILLING MODELS

more accurate

shows relative sizes of atoms

Computer-generated three-dimensional models are used to study large, complex

biological molecules, such as proteins and DNA.

chapter 4: properties of elements and compounds · chapter 4: properties of elements and compounds...

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