Entry Task: October 3rd-4th Monday

Question:

What is the difference between a heterogeneous mixture and

homogeneous mixture

You have 5 minutes!

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Physical and Chemical Properties

I Can…-Distinguish between a physical-chemical properties and changes.

-Apply the law of conservation of mass to chemical reactions.

-Distinguish between homogeneous and heterogeneous mixtures.

-Compare and contrast compounds, elements, and atoms.

Substances

Substances-are matter that has a uniform and UNCHANGING composition

Example: Water- pure water- is uniform (same through out) and its composition will ALWAYS be H2O

Physical Properties

Physical properties- are characteristics that can be observed or measured

without changing the samples’ composition.

color odor

boiling point

melting point

conduction density

malleable phase- at room

temperature

luster

solubility

Physical PropertiesWhat is the difference between extensive and intensive properties?Extensive properties are dependent upon the amount of substance that is there.Example- length, volume, shape

Intensive properties are independent of the amount of substance present.Example- density, or melting point or boiling point

What are chemical properties?

Chemical properties describes the ability of a substance to react with another substance.

Ability to catch on fire (flammability)

Ability to rust (corrosion)

Ability to burn skin (acid)

States of Matter

States of Matter

 Shape volume

Particle distance

Solids      

Liquids      

Gases      

Definite Definite Very close together

Undefined- shape of container

DefinedParticles slide past each other

Undefined- shape of container

Undefined- Volume

Compressible

Particles are very very far

apart

Physical ChangeWhen the appearance changes but not the composition of the substance remains the same is called a physical change.

Water is still water whether it’s a solid (ice) or gas (steam)

Hair is hair whether its long or cut short

Example: Freezing, cutting, crumpling, breaking, crushing and boiling

Chemical Changes

A process that involves one or more substances changing into new substances is called a chemical change.

Examples- rusting car, burning paper, rotting food, tarnish.

4Fe (solid) + 2 O2 (gas) 4FeO (rust)

How do you know if it’s going through a chemical change?

When observing a “change” at least 2 of these have to be present.

Temperature change

Presence of a gas (bubbles)

Color change

Odor change

Precipitate- solid floaters

Law of Conservation of mass

• That mass is neither created nor destroyed during a chemical reaction- it is conserved

Law of Conservation of massA chemical change results in a new substance being formed.

They rearrange to form a new substance.

What happens to the individual atoms during a chemical change?

Hydrogen molecule – H2

Hydrogen molecule – H2

+Oxygen molecule – O2

2 molecule of H2O- water

6. From a laboratory process designed to separate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was originally involved in the process?

If 10 grams of hydrogen and 79.4 grams of oxygen are collected, that means there is 89.4 grams of water to start.

7. A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete,the student obtained 39.7 g of sodium chloride. How many grams of chlorine gas reacted? How many grams of sodium reacted?

39.7 grams of sodium chloride was obtained. 15.6 of it was sodium so that makes 24.1 grams of chlorine was used.

15.6 grams of sodium.

8. In a flask, 10.3 g of aluminum reacted with 100.0 g of liquid bromine to form aluminum bromide. After the reaction, no aluminum remained, and 8.5 grams of bromine remained unreacted. How many grams of bromine reacted? How many grams of compound were formed?

10.3 g aluminum + (100g – 8.5 g= 91.5g) bromine = 101.8 grams of aluminum bromide

9. A 10.0-g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of oxygen reacted?

10 g of magnesium – 16.6 grams of magnesium oxide = 6.6 g of oxygen

By composition. What its made out of

Matter is sorted…

Mixtures AND Substances

What are the two broad categories of separating matter?

Matter

Mixtures Substances

Spices

Provide at least 5 examples.

blood

brass Dirt

Pizza

A mixture is a combination of two or more substances in which each of the substances retain their identity. They can be separated by physical means.

What are mixtures?

Define heterogeneous mixture.

A mixture that is NOT evenly distributed. These types of mixtures have two or more compositions and are called heterogeneous mixture.

Two kinds of Mixtures

These mixtures can be separated by physical means.

It can be very obvious-like a salad or difficult to catch- orange juice (pulp).

Define homogeneous mixture.

A mixture that IS evenly distributed. Homogeneous mixtures are composed of one composition.

These mixtures can be separated by physical means.

What are some types of solutions?

Homogeneous mixtures are the same composition through out the mixture.

Solutions ARE homogeneous mixtures.

Matter

Mixtures Substances

Heterogeneous Homogeneous-(Solutions)

Not the same through out

Same through out

physical

Chemical

What are compounds?

Are types of pure matter that can be broken down into simpler substances.

What are elements?

Are types of pure matter that can not be broken down into simpler substances.

SodiumChloride

Elements are the simplest form of matter.

Matter

Mixtures Substances

Heterogeneous Homogeneous-(Solutions)

Not the same through out

Same through out

physical

Fixed composition/properties

Compounds Elements

H2O

H2O2

CO2

Chemical

Can be broken down Can’t be

broken down

H2

O2

C

C12H22O11 Sugar

Examples of Substances

Au gold

NaCl Salt

C3H7OH AlcoholCO2

Dry Ice

Cl Chlorine I

Iodine

O Oxygen

H2O Wate

r

Na Sodium

S Sulfur

C12H22O11 Sugar

Sort the substances

Au gold

NaCl SaltC3H7OH

Alcohol

CO2 Dry Ice

Cl Chlorine

I IodineO

OxygenH2O

WaterNa

Sodium

S Sulfu

r

Elements Compounds

Define Law of definite proportions-

Law of multiple proportions

Regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.

H2O- 2 grams come from hydrogen and 16 grams of oxygen.

Basically- that different compounds CAN be made of the same elements but in different proportions.

H2O2 and H2O

I CAN…

Trace the history of the discovery atom and the theories behind it.

Explain the relationship between proton, electron and neutrons with atomic number and atomic mass.

Define an isotope and explain why atomic masses are not whole numbers

Ch. 4 pg. 87-104- The structure of the Atom

Background on the AtomGreek philosophers organized matter into combinations of 4 fundamental elements and how each changes into one another:

Summarize Democritus’s ideas about the atom

• Matter composed of empty space in which atoms moved.

• Atoms were solid, homogeneous and indestructible, and indivisible.

• Different kinds of atoms have different sizes and shapes.

• Differing properties of matter were due to the size, shape and movement of atoms.

• Apparent changes in matter were a result of groups of atoms not changes in the atoms themselves.

2000 years later…

Summarize Dalton’s ideas about the atom.• All matter is made up of atoms.

• All atoms in a given element are identical, having same size, mass and chemical properties- different from atom of other elements

• Atoms cannot be created, divided into smaller parts, or destroyed.

• Different atoms combine in simple whole number ratios to form compounds

• In a chemical reaction, atoms are separated, combined, or rearranged.

Define atom

• The smallest particle of an element that retains the properties of the element is called an atom

In the 1800’s most scientist believed that the atom as a teeny tiny solid sphere that was not made of anything smaller

What is a cathode?

• It’s the negative terminal of a battery.

What is a anode?

• It’s the positive terminal of a battery.

What is a cathode ray?• A Cathode ray is a vacuum tube that had a

positive end (anode) and a negative end (cathode) in which particle from the cathode traveled to the anode end creating a flash of light

Variations to the cathode ray

Because the cathode ray is deflected towards the positively charged plate by an electric field, the particles in the ray must have a negative charge.

By the end of the 1800’s, what were scientists fairly convinced of?

• Cathode rays were actually a stream of particles

• The particles carried a negative charge. (The exact value of the negative charge was not known, however.)

Summarize J.J. Thomson’s experiment that leads to the discovery of the electron.

• Tried to determine the mass of 1 particle in the cathode beam.

• Determined the mass-charge ratio• Found that his particle had a much lower ratio than

hydrogen- the lightest known atom.• This means there are particles smaller than an

atom.• Daltons theory is wrong- atoms are divisible.

Summarize Millikan’s experiment.

• Determined the exact charge to mass ratio of an electron

• He found that a single electron has a mass of an electron is 9.1 X10-28th the mass of hydrogen.

• This means that it would take 1840 electrons to have the mass of 1 atom of hydrogen.

Evidence for models of the atom

• Atoms are made of negative particles• Since our world is neutral (electrically) there

HAS to be a complementary positive particle to balance this out.

• The positive particle has not been discovered yet so what does the atom “look” like”. Plum Pudding model.

Plum pudding model

Summarize Rutherford’s experiment.• Aimed a beam of alpha particles at a thin layer of gold

foil and zinc sulfide detector behind it would detect the particles path as is went through the foil.

Summarize Rutherford’s experiment.• Expected minor deflections by the tiny electrons and

because the positive charge was uniform in the atom that that would not cause any deflections either.

Describe Rutherford’s nuclear model of the atom.

• Result: mostly no deflections and some major deflections occurred.

• Atom is mostly empty space and there is a dense region in the middle (nucleus) which contained all the positive charge for an atom and most of the mass

Define proton.

• It’s a subatomic particle carrying a charge equal to but opposite that of an electron; that is, a proton has a positive charge of 1+.

Define neutron.

• It has a mass equal to a proton but carries no electrical charge- neutral.

Define Atomic Number

• Is the number of protons in the nucleus.

What is the atomic number the same as?

• Atomic # = # of protons = # of electrons

What are isotopes?• Atoms with the same number of protons but

differ in the number of neutrons are isotopes

Define Mass Number

• Is the sum of the number of protons + neutrons in the nucleus of an atom.

What is the difference between atomic mass units and atomic mass?

• The atomic mass is the sum of the masses of particles.

• Atomic mass units is a calculated mass relative to the mass of particles in a carbon atom. 1 amu is 1/12th the mass of a carbon atom.

Your Task tonight

• Ch. 4 section 1 and 2 ws.