Chemical Bonds
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Ion

Atom with either more protons
or with more electrons
 Can only lose or gain electrons
(remember, protons don’t
move)
Polyatomic Ion
 More than one ion bonded
together, to create a neutral
atom
Stable-0 or 8 valence electrons
Atom-neutral charge, but not
stable
Ion-positive or negative charge,
but stable
Ionic Bonding
 Form Compounds
 Attraction between two
oppositely charged ions
Covalent Bonding
 Form Molecules
 Two atoms share electrons
 Often are formed by two
nonmetals
Ionic Bonds
Bonds between two ions
Ion- atom, or group of atoms that has become electrically charged
Atoms have the same # of protons and electrons-when gain or lose electrons,
electric charge occurs
Electron Transfer
Remember-atoms want stability
5, 6, or 7 V.E. gain electrons
1,2, or 3 V.E. lose electrons
Gain or lose to become stable
Electron Transfer
When an atom loses electrons, they are losing a negative charge (-)
Therefore, it now has 1 more proton
Now has a positive charge (+)
When gaining an electron, they are getting one more electron than proton
Therefore, it now has a negative charge (-)
Ionic Bonding
Attraction between two oppositely charged ions
Ex NaCl
Na becomes a (+) ion
Cl becomes a (-) ion
Charges are balanced
Polyatomic Ion
Ions made from more than 1 atom
Group of atoms that have an overall positive or negative charge
Polyatomic ion + another ion of apposite charge= polyatomic compound
Ex: Carbonate ion (CO3 2-) is made from 3 Oxygen atoms and 1 carbon atom and
has a 2- charge
It will combine with a calcium ion of 2+
Naming Ionic Compounds
Name of (+) ion is first, followed by (-) ion
Positive ion is usually a metal
If (-) ion is an element, -ide is added
Ex. MgO= magnesium oxide
If (-) ion is polyatomic, name is unchanged
Ex. Na2CO3=sodium carbonate
Properties of Ionic Compounds
Crystal shape
High melting points
Strong bonds cause compounds to be solids at room temperature. Takes
high energy/high temperature to break these bonds
Dissolvability
Many ionic compounds dissolve in water. The ions then become
surrounded by water. These dissolved ionic compounds are very
important to all living things and many are found in cells.
Electric conductors
When melted or dissolved (now in liquid form), the ions can move more
freely, therefore allowing electricity to flow
Covalent Bonding
Two atoms share electrons
Often are formed by two nonmetals
Both atoms attract to share a bond
The number of bonds formed depends on the VE
Ex. Oxygen has 6 VE, it will take two Hydrogen atoms to form a bond
Can from 2, 3, bonds or more
Covalent Bonds
Molecular Bonds-bonds that are formed by CB
All have different properties
Most are poor conductors
Polar/Non-polar Covalent Bonding
Some electrons pull harder-like tug-of-war
This causes a slight electrical charge
Not as strong as ions
These are called polar
Non-polar have an equal pull
Molecule Attraction
Slight charges cause molecules to behave weird
Ex. Oil and water
We use these different attractions to our benefit
Ex. Laundry detergent
Molecular Compounds
Covalent bonds
Weak forces hold them together
Therefore, takes low energy (low temp.) to break bonds apart
Poor conductivity
No charged particles (ions or loose electrons)
Covalent bonds
Molecules
Definite size
Solid, liquid or gas
More common EX. Carbohydrates, proteins, fats, oxygen, vitamins
Nonmetals and nonmetals
Ionic bonds
Compounds
Unlimited size
Almost always solids
More rare
Metal and Nonmetals