INTRO TOINTRO TOCHEMISTRYCHEMISTRY

Biology I

MatterMatter Anything that occupies spaceoccupies space and has

massmass.

Examples:Examples:

1.1. rockrock

2.2. woodwood

3.3. metalmetal

4.4. airair

Matter is divided into 3 states

Solids have both a definite volume & definite shape (rock)

Liquids have a definite volume but no definite shape; they can be poured (water)

Gases do not have a definite volume or definite shape, but they take the volume & shape of their container

Matter consist of atoms, which are the smallest unit of matter that can’t be

broken down.

Most atoms consist of 3 particles:Electrons---Protons---Neutrons

Components of anComponents of an AtomAtom

ComponentComponent Charge Charge LocationLocation

1.1.ProtonProton positivepositive nucleus nucleus

2.2.NeutronNeutron neutralneutral nucleus nucleus

3.3.ElectronElectron negativenegative around the around the nucleusnucleus

Atoms

The simplest particle of an element that retains all the properties of that element

Properties of atoms determine the structure and properties of the matter they compose

Our understanding of the structure of atoms based on scientific models not observation

The Nucleus

Central core Consists of positive

charged protons and neutral neutrons

Positively charged Contains most of the

mass of the atom

The Protons

All atoms of a given element have the same number of protons

Number of protons called the atomic number Number of protons balanced by an equal

number of negatively charged electrons

The Neutrons

The number varies slightly among atoms of the same element

The Electrons

Negatively charged high energy particles with little mass

Travel at very high speeds at various distances (energy levels) from the nucleus

Chemical ElementsChemical Elements

ElementsElements are pure substances which cannot are pure substances which cannot be chemically broken down into simpler be chemically broken down into simpler kinds of matter.kinds of matter.

More than 100 elements have been More than 100 elements have been identified, but only about 30 are important identified, but only about 30 are important in living things in living things

All of the Elements are arranged on a chart All of the Elements are arranged on a chart known as the known as the Periodic TablePeriodic Table

Periodic charts tell the atomic number, Periodic charts tell the atomic number, atomic mass, & chemical symbol for every atomic mass, & chemical symbol for every element  element  

Four elementsFour elements, Carbon – C, Hydrogen – H, , Carbon – C, Hydrogen – H, Oxygen – O, and Nitrogen – N make up Oxygen – O, and Nitrogen – N make up almost 90% of the mass of living thingsalmost 90% of the mass of living things

Chemical Elements Chemical Elements cont..cont..

Each element has an unique chemical symbol Consists of 1-2 letters First letter is always capitalized

The number of protons in an atom is called the atomic number & determines which element it is.

The number of protons & neutrons is called the atomic mass or mass #.

How do we find the #of neutrons?

Atomic mass (# of neutrons & protons)

- Atomic # (# of protons)

= # of neutrons

10

12835

ELECTRONS The number of positively charged protons is

balanced by an equal number of negatively charged electrons (e-).

Electrons at outer levels have more energy than those in inner levels.

Each level or shell can only hold a certain # of e- The first level, nearest the nucleus can only hold

two electrons, the second and other outer levels can hold up to eight electrons each.

A stable atom is an atom that has a full outer level

Electrons in the same energy level are approximately the same distance from the nucleus

Outer energy levels have more energy than inner levels

Each level holds only a certain number of electrons

A T O M S

CompoundCompound

Substance containing two or more two or more elementselements.

Example:Example: CC66HH1212OO66 (glucose - (glucose -

sugar)sugar)

6 - carbons6 - carbons

12 - hydrogen12 - hydrogen

6 - oxygen6 - oxygen

Question:Question:

Answer the following questions aboutAnswer the following questions about CC66HH1212OO66

1. How many elementselements are involved?

2. How many atomsatoms are involved?

Answer:Answer:

11. ElementsElements - - 3 (C, H, O)3 (C, H, O)

2. 2. AtomsAtoms - - 2424

AtomAtom

The smallest unit of mattersmallest unit of matter that still retains the properties of an elementelement.

Carbon - AtomCarbon - Atom

Protons Protons - 6- 6

NeutronsNeutrons - 6- 6

Electrons- 6Electrons- 6

Atomic NumberAtomic Number

EqualsEquals the number of protonsnumber of protons within the nucleus of an element.

Examples:Examples:

Hydrogen (H)Hydrogen (H) - 1- 1

Sodium (Na)Sodium (Na) - 11- 11

Carbon (C)Carbon (C) - 6- 6

Oxygen (O)Oxygen (O) - 8- 8

Gold (Au)Gold (Au) - 79- 79

Atomic MassAtomic Mass

EqualsEquals the number of protons + neutronsprotons + neutrons.

Examples:Examples:

Hydrogen (H)Hydrogen (H) - 1.0079- 1.0079

Sodium (Na)Sodium (Na) - 23- 23

Carbon (C)Carbon (C) - 12- 12

Oxygen (O)Oxygen (O) - 16- 16

Gold (Au)Gold (Au) - 197- 197

Charge of an ElementCharge of an Element Question:Question: protonsprotons = electronselectrons

Answer:Answer: charge is neutralneutral

Question:Question: protons protons electronselectrons

Answer:Answer: the charge is either either negativenegative or or positivepositive

IsotopeIsotope AtomsAtoms of elements with different

number of neutronsneutrons.

Examples:Examples:

carbon - 12carbon - 12

carbon - 13carbon - 13

carbon - 14carbon - 14

Isotopes of CarbonIsotopes of Carbon

NucleusNucleus 1212CC 1313CC 1414CC

protonsprotons 66 66 66

neutronsneutrons 66 77 88

electronselectrons 66 66 66

ElectronsElectrons orbit around the nucleusnucleus

first bonding orbital - 2 electrons2 electrons

all other bonding orbitals - maximum 8 electronsmaximum 8 electrons

orbitals have certain energy levelsenergy levels

orbitals farther from the nucleus have the highest

energy level.

Sodium and Chlorine – Sodium and Chlorine – Electrons Bonding OrbitalsElectrons Bonding Orbitals

NaNa ClCl

Chemical BondingChemical Bonding ThreeThree types of bondsbonds with different different

strengthsstrengths:

covalent > ionic > hydrogencovalent > ionic > hydrogen

Covalent BondsCovalent Bonds strongest bondstrongest bond two elements shareshare one or more pairsone or more pairs

of outer electrons singlesingle and double bondsdouble bonds Examples:Examples:

1. H2O (water - polar molecule)

2. CH4 (methane)

3. O2 (dioxide)

O-

H+

H+

O=O

H-C-HH

H

IonIon atom or molecule with an electric electric

chargecharge.

resulting from a gain or loss of one or gain or loss of one or more electronsmore electrons.

Examples:Examples:

Sodium ion (NaSodium ion (Na++))

Chloride ion (ClChloride ion (Cl--))

Ionic BondsIonic Bonds second strongest bondsecond strongest bond

two ions with opposite charges two ions with opposite charges attract to each other.attract to each other.

Examples:Examples:

salts (NaCl)salts (NaCl)

acidsacids

basesbases

Ionic BondIonic Bond Example:Example: salt (Nasalt (NaCl)Cl)

ClClNaNa

Hydrogen BondingHydrogen Bonding weakest of the three bonds.weakest of the three bonds. Most important and common of all Most important and common of all

bonds.bonds. Partially positive hydrogenPartially positive hydrogen atom of one

molecule is attracted to the partially partially negative atom negative atom of another molecule (O or (O or N).N).

Example:Example: HH22OOO-O-

H+

H+

H+ H+H+ O-

H+

H+ O-

H+

hydrogen bonds