groups - review each column is called a “group” each element in a group has the same number of...
TRANSCRIPT
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