Title: Chemical Bonding
1Chemical Bonds
2Chemical BondingWhat holds things together?
3Bonding
- Involves the valence electrons or outermost
electrons - Outermost electrons in the last energy shell
How many valence electrons does N have?
Group 5A 5 valence electrons
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5Bonding
- Lewis dot structures show the valence electrons
around at atom and for most molecules and
compounds a complete octet for the elements
Al
N
6Write out the electron configuration for the
following atoms and ions
He Ne Ar Kr
7NaCl
This is the formation of an ionic bond.
-
Na
Cl
electron transfer
and the formation of ions
Cl2
This is the formation of a covalent bond.
sharing of a pair of electrons
and the formation of molecules
8Ionic Bond
- Between atoms of metals and nonmetals with very
different electronegativity - Bond formed by transfer of electrons
- Produce charged ions all states. Conductors and
have high melting point. - Examples NaCl, CaCl2, K2O
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10Ionic Bonds One Big Greedy Thief Dog!
111). Ionic bond electron from Na is transferred
to Cl, this causes a charge imbalance in each
atom. The Na becomes (Na) and the Cl becomes
(Cl-), charged particles or ions.
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13COVALENT BONDbond formed by the sharing of
electrons
14Covalent Bond
- Between nonmetallic elements of similar
electronegativity. - Formed by sharing electron pairs
- Stable non-ionizing particles, they are not
conductors at any state - Examples O2, CO2, C2H6, H2O, SiC
15Covalent Bonds
16Chlorine atom 2,8,7
172 Chlorine atoms Outer shells only
18Chlorine molecule Cl2
Electrons shared
Each outer shell has 8 electrons
Forces (bonds) between atoms in the molecule very
strong
Forces between molecules very weak
Molecular or covalent compounds are usually gases
or liquids they have low melting points and
low boiling points
Molecules have no overall electric charge
19Covalent Bonds Water H2O Methane CH4 Ammonia
NH3 Hydrogen H2 Hydrogen Chloride HCl Oxygen
O2 N.B. Oxygen has a double bond
20Oxygen
Oxygen atom 2,6
212 Oxygen atoms (outer shells only)
Double covalent bond
22More sharing examples
O2
Share until octet is complete.
N2
octet complete
23Some more sharing examples
NH3
N
24Comparison of Bonding Types
ionic
covalent
ions
molecules
conductive
non- conductive
valence electrons
transfer of electrons
sharing of electrons