Groups - Review

•Each column is called a “group”

•Each element in a group has the same number of electrons in their outer orbital, also known as “shells”.

Except for He, it has 2 electrons

•The electrons in the outer shell are called “valence electrons”

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Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like toO would like to

Gain 4 electronsGain 4 electronsGain 3 electronsGain 2 electrons

Lewis Structures1. Find # of valence electrons for the

element 2. Write the chemical symbol for the

element3. Place 1 dot per valence electron

around the elements counter clockwise (fill up singly before doubling)

4. Each side of the element can only have two dots, because each orbital can only hold 2 electrons

5. Lone electrons tell you how many bonds will form

1 dot = 1 electron

Lewis Structures1) Write the element

symbol.

2) Carbon is in the 4th group, so it has 4 valence electrons.

3) Starting at the right, draw 4 electrons, or dots, counter-clockwise around the element symbol.

Electron Configuration

1s2, 2s2, 2p2

Examples

1. Li

2. Al

3. S

4. Kr

How many bonds will they form?

Learning Check

A. X would not be the electron dot structure for

1) Na 2) K 3) Al

B. X would not be the electron dot formula

1) B 2) N 3) P

Vocabulary

Chemical Bond

attractive force between atoms or ions that binds them together as a unit

Vocabulary

Ionic Bond

Bond formed between two ions by the transfer of electrons

Properties of Ionic Bonds

1. When a metal (+) and a non-metal (-) combine

2. Oppositely charged ions attract

3. Soluble in water

4. Conducts electricity when dissolved

Learning Check

A. Number of valence electrons in aluminum1) 1 e- 2) 2 e- 3) 3 e-

B. How will aluminum get an octet1) lose 3e- 2) gain 3 e- 3) gain 5 e-

C. Ionic charge of aluminum 1) 3- 2) 5- 3) 3+

Vocabulary

Covalent Bond

Bond formed by the sharing of electrons

Covalent Bond

• Found to the right of the staircase• Between 2 non metals of similar

electronegativity.• electronegativity – the tendency for an atom

to attract electrons to itself when it is chemically combined w/another element

• Examples; O2, CO2, C2H6, H2O, SiC

Bond Polarity

Difference in electronegativity determines bond type

-- Above 1.7 = ionic

– 0.3-1.7 = polar covalent

– 0-0.3 = non-polar covalent

Look at periodic table in CRM (p 12). Find the difference between the two #’s (positive #)

Which is more polar covalent?

(Larger # = more polar)

O-O or O-H

Bonds in the polyatomic ions and diatomics

molecule are all covalent bonds

Vocabulary

Nonpolar Covalent Bonds

When electrons are shared equally

H2 or Cl2

Vocabulary

Polar Covalent Bonds

When electrons are shared but shared unequally

H2O

Vocabulary

Metallic Bonds Bond found in metals; holds metal atoms

together very strongly

Good conductors at all states.

Lustrous

Very high melting points

Metallic Bond

* Metals do NOT combine with metals. They form alloys which is a solution of a metal in a metal.

Examples are steel, brass, and bronze

Metallic bonds are referring to the bonds between the atoms of a single metal