Atomic Bonding
Valence ElectronsRemember these are the outer-most electrons and the only ones involved in bonding
The max and magic number is 8 (Unless you are hydrogen and helium, they only need
2)
The group number helps tell you how many valence each element has.
So which group will essentially never bond- aka INERT?
Ionic Bonding- Electrons are stolen!
One element has the majority of electrons so it will “steal” electrons to reach 8 valence.
Example- Na = 1 valence Cl= 7 valence It is easier for sodium to just get rid of one
and chlorine REALLY needs that electron
*Na is in group 1, Cl is in group 17
(special note, this is why group 7 is called the Halogens- or “salt formers”)
IONIC bonds are always between a
METAL and a NON METAL
Called compounds
IONS are formed
Na has a +1 charge because it LOST an electron, it has one extra positive particle
= Cation (think the t looks like a +) (metal)
Cl now has a -1 charge because it has and extra negative particle
= Anion ( A Negative ION) (non-metal)
The 2 charges balance each other out
Is it always one electron stolen?
Nope- its however many are needed to reach 8… EXAMPLE
Mg is in group 2, so 2 valence electrons… Bromine is in 17, so 7 valence electrons...
Mg has 2 to give away, Bromine only has one space- so 2 atoms of bromine are needed,
← Another example
Covalent Bonds- Sharing is Caring!
In a covalent bond, electrons are passed back and forth/ shared.
The goal is to still reach 8, except again H and He
Example- H has 1, C has 4.
So 4 Hs are needed to fill the 4 spaces C needs,
but H also uses some of C electrons to fulfill
its need of 2 each.
Other Covalent Bonds
Not every electron needs to be shared, just enough for each one to reach 8, H fills
spots, the rest of the nonmetals just share as many as necessary
Polar vs. Nonpolar
Some elements don’t like
to exactly share equally- so
it’s called a POLAR bond.
*like WATER!
One end is slightly
more negative the other
slightly more positive.
COVALENT bonds are always between
2 NON METALS
Often called Molecules, but also called
compounds
But wait- what about metalloids? Generally, because they share characteristic of both
metals and non-metals, its all about the specific bond for them...
Metallic bonds- only between metals
Valence electrons “detach” from their respective elements and form a “sea” of
electrons. The metal atoms form positive ions. This trait allows metals to conduct heat,
electricity, makes it malleable. These atoms are lined up in an organized fashion and
the electrons help them hold their shape.
Polyatomic Bonds
“Many atoms”
Ions/ Compounds that have more than one type of bond-
Mg to SO = ionic
S to O = covalent
Other words you might hearOxidation Number- a + or - number which is assigned to an element when it has
formed a bond, these are used to help keep track of the electrons.
Electronegativity- Pauling Scale
The tendency of an element or compound to attract electrons, especially when it is
close to having a full 8/ valence shell