Chemistry: The Study of Matter

MatterAnything that has mass or takes up

volumeCannot be created nor destroyedExists in four states:

◦Solid ◦Liquid◦Gas◦Plasma

Classification of Matter

All Matter is made up of ATOMSAtoms

◦An atom is the smallest particle of an element that still has the properties of that element

◦“ There are possibly more atoms within this single grain of sand than there are grains of sand in this entire beach”

Atoms are made up of subatomic particles

PROTONS (+)- Particles in nucleus with a positive charge!

ELECTRONS (-)- Particles outside the nucleus with a negative charge!

NEUTRONS- Particles in nucleus with no charge!!!!!

Protons & neutrons are held tightly at the centre of the atom in a small region called the NUCLEUS

The NEUTRAL ATOM….. Neutral atom

has the same number of protons and electrons

Most of an atom’s atomic mass comes from the nucleus

Nuclear Charge - Equal to the number of proton charge

ATOMIC NUMBER

Not important yet!!!

PROTONS & ELECTRONS in an ATOM

ATOMIC NUMBER

# OF PROTONS # OF ELECTRONS

= =

How many protons are in this sodium atom?

How many electrons are in this sodium atom?

11

11

Number of NEUTRONS in an ATOMNumber ofNEUTRONS

RoundedAtomic Mass

Number of Protons

= —

ATOMIC MASS

ATOMIC NUMBER

What is the number of protons?

What is the number of electrons?

What is the number of neutrons?

15

15

31-15 = 16

Element Atomic number

# of protons

# of electrons

Electrical Charge

Rounded Atomic Mass

# of neutrons

Hydrogen

Atomic number = # of protons = # of electronsNumber of neutrons = Atomic mass - # of protonsElectrical charge of an atom is neutral

1 1 1 0 1 0

Element Atomic Number

# of protons

# of electron

sElectrical Charge

Rounded atomic

Mass

# of neutron

s

Hydrogen 1 1 1 0 1 0

Potassium 19 19 19 0 39 20

Phosphorus 15 15 15 0 31 16

Sulfur 16 16 16 0 32 16

Magnesium 12 12 12 0 24 12

Calcium 20 20 20 0 40 20

Bohr Diagrams for ATOMSBohr diagram shows how many

electrons are in each electron shell around an atom

The outer most shell is called the valence shell

KELECTRON SHELLS

VALENCE SHELL!!!

Bohr Diagram for ATOMSTo draw Bohr Diagrams:1. Determine the number of electrons2. Write the element symbol3. Determine number of shells4. Fill the shells according to the following:

1. The first shell holds only 2 ELECTRONS

2. The second shell holds 8 ELECTRONS

3. The third shell holds 8 ELECTRONS

Bohr Models for ATOMSElement Atomic

number

Total # of electrons

Electrons in first shell

Electrons in 2nd Shell

Electrons in 3rd shell

He

He

1. Determine # of electrons2. Write the elemental symbol3. Determine number of shells

2 2 2 0 0

4. Fill electrons according to 2, 8, 8 rule

Bohr Models for ATOMSElement Atomic

number

Total # of electrons

Electrons in first shell

Electrons in 2nd Shell

Electrons in 3rd shell

C

C

1. Determine # of electrons2. Write the elemental symbol3. Determine # of shells

6 6 2 4 0

4. Fill shells with electrons with the 2, 8, 8 rule

Bohr Models for ATOMSElement Atomic

number

Total # of electrons

Electrons in first shell

Electrons in 2nd Shell

Electrons in 3rd shell

Cl

Cl

1. Determine # of electrons2. Write the elemental symbol3. Determine # of shells

17 17 2 8 7

4. Fill shells with electrons

Phosphorus

Sodium

ORGANIZATION OF PERIODIC TABLE

The periodic table is organized:- according to the atomic number- according to electron patterns - into rows called periods- into columns called groups / family- metals on the left - transition metals in the middle- non-metals on the right - Metalloids form the staircase

Columns are called GROUPS

Rows are called PERIODS

PERIODIC TABLE ORGANIZED ACCORDING TO ELECTRONS

The Period (row) tells you number of ShellsOne shell

Two shells

Three shells

The Group/ Family (column) tells you number of valence electrons

1 valence e-

2valence e-

3valence e-

4valence e-

5valence e-

6valence e-

7valence e-

Fullvalence e-

GOAL of elements at ATOMIC LEVEL

TO HAVE A FULL VALENCE SHELL!!!!!!!!!!!!!

The closer they are to the full valence shell, the more desperate they get!! Therefore, more reactive!

Group 1 = ALKALI METALSDesperate to give away 1

electron!!!!VERY REACTIVE!!!!

Group 1 = ALKALI METALS

Group 2 : Alkali Earth MetalsNot as desperate.... Not as

reactive Wants to give away 2 electrons

Group 17 : HalogensVery reactive!!!!!Wants to TAKE 1 more

electron!!!Reacts with alkali metals

Group 18: Noble GasesThey have a FULL valence

shellThey’re happy and very

STABLENot reactive

IONSWhen atoms gain or lose

electrons they become electrically charged and form IONS

F F

1-

Positive Ion is called CATIONNegative Ion is called ANION

IONS ELECTRICAL CHARGEIf Lithium has 3 protons.....And it usually has 3 electrons......BUT IT LOSES AN ELECTRONHow many electrons does it

have?2!!!

ELECTRICAL CHARGE = +1

3 protons = + 3 2 electrons = -2

ION’S ELECTRICAL CHARGE

How many electrons does it have?

If Fluorine has 9 protons.....And it usually has 9 electrons......BUT IT GAINED AN ELECTRON

10!!!!

ELECTRICAL CHARGE = -1

9 protons = + 910 electrons = -10

IONSATOMIC NUMBER = Number of Electrons IN AN ATOM

Atomic mass:Atomic mass – # of protons= number of neutrons

This is very important for IONS, it is the IONIC CHARGE

Positive charge = lost electron

Negative charge = gained electron

Remember!!!Positive Charge means an

electron was LOST

Negative charge means an electron was GAINED

Bohr Models for IONS

Cl

1. Determine atomic # & number of electrons in atom 2. Determine electrical charge3. Did you gain or lose electron?4. Draw Bohr Model

Element

Atomic number

# of e- in an ATOM

Electrical Charge

Gain? Or lose electron?

# e- of in an ION

Electron shells filled

Cl 17 17 Gain 1

18 21 -

1-

5. Add ionic charge

8 8

+ 17 – 18 = -1

Bohr Models for IONSElement

Atomic number

# of e- in an ATOM

Electrical Charge

Gain? Or lose electron?

# of e- in an ION

Electron shells filled

Li 3 3 Lose 1

2 21 +

1+

0 0

Li Li + 3 – 2 = + 1

Forming CompoundsWhen 2 atoms get close together,

their VALENCE ELECTRONS INTERACTIf atoms can form a stable bond, a compound is formed

Remember, the goal is to GET A FULL VALENCE SHELL

Forming Compounds

There are 2 types of compounds◦IONIC COMPOUND◦COVALENT COMPOUND

IONIC COMPOUNDSIonic compounds form ionic bonds

In ionic bonding, electrons are transferredAn ionic compound consists of metal and non-metals

After the electrons are transferred, the ions are attracted to each other and form a bond

The metals donates/loses electronsThe non-metals gains/ accepts electrons

Example 1: Ionic Bonding

Example 2: Ionic BondingYou have lithium and oxygen

Li O

How many Lithiums do you need to make Oxygen Happy?2!!!

lithium oxygen

+

Electrons are transferred from the positive ions to negative ions

Li+ O2- Li+

lithium oxide, Li2O

COVALENT COMPOUNDSCovalent compounds form covalent

bondsIn a covalent bond, atoms SHARE ELECTRONS between non-metals

This results in their shells overlapping

hydrogen

+

fluorine electrons are shared

Hydrogen fluoride

It is the Valence shells that determine reactivity. Lets just look at the valence shells!

Electron pairs NOT used in bonding are called LONE PAIRS

Electron pairs involved in a covalent bond are called BONDING PAIRS

Diatomic MoleculesMolecules where 2 of the same atoms

are covalently bonded are called diatomic molecules.

The following are diatomic molecules

O2 I2 H2 Br2 Cl2 F2

I Have No Bright Or Clever Friends

N2

LEWIS DIAGRAMSLewis diagrams only show the

valence electrons and chemical symbol to represent chemical bonding

Only need to draw valence electrons!

Lewis Diagrams for ATOMS

Before

After

Lewis Diagrams for IONS

Cl

1. Determine Group Number2. Determine valence electrons in ATOM and electrical charge

4. Determine number of valence e- in an ION

Element Group Number

Valence electrons in ATOM

Electrical Charge

Gain? Or lose electron?

Valence electrons in ION

Cl 17 7 Gain 1

81 -

1-

5. Add ionic charge 1-

3. Gain or lose e-

Lewis Diagrams for IONS

Element Group Number

Valence electrons in ATOM

Electrical Charge

Gain? Or lose electron?

Valence electrons in ION

Na 1 1 Lose 1

01 +

Na

1-

Na

Lewis Diagram for CompoundsDots show the pairs of electrons in

the valence shellLines represent bonds or e- sharedGOAL OF ATOMS: gain a FULL

valence shell

H F H FBonding Pairs!!!!!!

Lone Pairs!!!

Na Cl Na

Cl

OH OHH

OHHBonding

Pairs!!!!!!

Lone Pairs!!!