chemical bonds unit 6 chapter 6 ionic covalent metallic
Post on 15-Jan-2016
225 Views
Preview:
TRANSCRIPT
Chemical BondsUnit 6
Chapter 6
IONIC
COVALENT
METALLIC
I. Why do atoms bond?A. Atoms bond in order to become stable
B. Electron configurations of the noble gases are stable.
1. Helium is stable with 2 valence e-.2. All others are stable with 8
valence e-.
C. Atoms of unstable electron configurations will gain, lose, or share electrons to become stable like a noble gas.
not stable stable
not stable stable
II. Electron Dot Notation
A. Only valence electrons are used in bonding
B. Electron dot notation highlights the valence electrons
Al Ca F Cs
12 3 4 5 6 7
8
Representative Group Valence Electrons
How to draw the electron dot notation of an atom:
Step 1: Write the chemical symbol
Step 2: Imagine a box around it
Step 3: Draw a dot for each valence electron Dots only go on the SIDES of the box
Rule: One dot per side before you double up
As
As
As
As AsYES!
Now you try some.
Li Cl Ne
Sr C Mg
Pb N I
What would happen if sodium and chlorine bump into each other?
An electron would transfer from the Na atom to the Cl atom so that each atom would become a stable ion.
Net charge +1 Net charge -1
III. Ionic BondsA. Metal – Nonmetal
B. Electrons are transferred from the metal to the nonmetal
C. Ions are produced
D. Ion attraction makes the bond
(+) (-) Na+1 Cl-1
E. A Crystal is formed
Ca I Ca I
Let’s Practice!
K Br
Before bonding After Bonding Chemical Formula
K Br KBr
I ICaI2
+1 -1
+2-1
-1
Ion net charge = zero!
Ion net charge = zero!
A. Nonmetal – Nonmetal
B. Electrons are shared
C. Molecules are produced
D. Sharing makes the bond (tug-o-war)
F F or F F
IV. Covalent Bonds
2 Shared electrons 2 Shared electrons
E. Can have double and triple bonds
Double: O O or O O 4 Shared electrons 4 Shared electrons
Triple: N N or N N 6 Shared electrons 6 Shared electrons
(a stronger bond)
(the strongest bond)
F. Diatomic elements are formed as follows:
H2 N2 O2 F2
Cl2 Br2 I2
BrINClHOF
Let’s Practice!Before bonding After Bonding Chemical Formula
C H
H
H
H HH C H H
CH4
All atoms are stable!
Now you try some.
1. N and F
2. H and O
3. Diagram the molecule C2H6O
Answer to #1:
N F
F
F
FF
F N F NF3
before after formula
Answer to #2:
HO
H
H OH
H2O
before after formula
Answer to #3: C2H6O
O HC
H
H
H
H
C
H
C
H
H
H
O
H
C
H
H
or
A. metal – metal
B. Electrons are pushed from atom to atom.
C. Electrons are free to move among the metal atoms allowing metals to conduct electricity. (see picture below)
D. A mixture of metals is called an Alloy.
V. Metallic Bonds
A. Formula Writing1. Cation first, anion second
Ca+2 Cl-1
2. Net charge must equal zero
Ca+2 Cl-1 Cl-1 = zero (It takes 2 chloride ions to stabilize the Ca)
3. Write the formula: CaCl2
VI. Ionic Binary Chemicals
B. Naming1. The metal ion has the same name as the metal atom.
Ca+2 is named calciumK+1 is named potassium
2. Some metals form more than one ion. These metals require a roman numeralafter their name to indicate which ion isin the chemical formula.
Fe+2 is named iron (II)Fe+3 is named iron (III)
NO roman numeral in the name, elementonly produces one common ion.
Roman numeral is necessary, elementcontains more than one common ion.
3. The nonmetal ion will end with the suffix -ide.
Examples:
S-2 is named sulfideF-1 is named fluoride
O-2 is named oxideP-3 is named phosphideN-3 is named nitride
A. Formula Writing1. Follow the ionic rules.
2. Ternary chemicals contain a polyatomic ion.
polyatomic ion- a group of covalently
bonded atoms that act as a single ion
examples: CO3-2 NH4
+1
VII. Ionic Ternary Chemicals
3. RULE: If more than one polyatomic ion is needed to write the
chemical formula use parenthesis.
example: Ca+2 NO3-1
NO3-1
CaNO32
zeronet charge
Ca(NO3)2
YES, two NO3-1 ions!(looks like we have 32 oxygen atoms)
B. Naming 1. Follow the ionic rules.
2. Examples:
Al(OH)3 is named aluminum hydroxide
Cu(NO3)2 is named copper (II) nitrate
K2CO3 is named potassium carbonate
A. Greek prefixes are used to identify the number of each element in a covalent compound.
mono = 1di = 2tri = 3tetra = 4penta = 5hexa = 6hepta = 7
VIII. Covalent Chemicals
B. Rule: mono- is never used for the first
element in the compound.
C. Sometimes the last letter of the prefix is dropped if the name of the element starts with a vowel.
D. Examples:
CO2 is named carbon dioxideCO is named carbon monoxidedinitrogen monoxide is written as N2O
top related