Chemical Bonding

ionic bond

Formed when one or more electrons are transferred from one atom to another

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

The type of chemical bonds that forms between atoms has to do with the _____.

difference in electronegativity between the atoms participating in the bond

What is electronegativity?

Electronegativity is the amount of pull an atom will have on an electron, The ability of an element to attract nearby valence electrons

Why do ionic bonds happen?

Ionic bonds: occur between metals and nonmetals who have a large electronegativity difference, causing electrons to be passed from the metal to the nonmetal. The now charged ions are attracted to each other.

What happens to electrons in an IONIC BOND?

electrons go from metal to nonmetal

Why do covalent bonds happen?

Covalent Bonds: occur between nonmetals with a smaller electronegativity difference. Electrons are shared between the atoms to meet the octet.

What happens to electrons when the electronegativity is less than 1.7?

shared

the more electronegative...

The more electronegative the atom is, the more likely it will pull the electrons towards itself

The _____ electronegative atom in a polar covalent bond pulls the electrons towards itself.

more

As a result of the slight electron excess, the more electronegative atom in a polar covalent bond becomes partially _____.

negative

Partially negative is denoted by the symbol

delta minus, δ-

What is the difference between polar and nonpolar covalent bonds?

In polar covalent bonds electrons are shared unequally, and in nonpolar covalent bonds electrons are shared equally.

how to tell if the bond is going to be ionic or covalent

Electronegativity differences and bonding:

less than .5 -- nonpolar covalent bond

.5 - 1.7 -- polar covalent bond

more than 2.0 ionic

Why do metals and non-metals form ionic bonds but multiple non-metals form covalent bonds?

electronegativity

nonpolar covalent bond

0.0-0.4 ( relativly equal sharing)

polar covalent bond

0.4-1.7(unequal sharing)

ionic bond

1.7-3.3 (equal sharing)

What do the lines represent?

Lines represent covalent bonds between atoms

phosphorus and sulfur...

form expanded octets

boron, beryllium, and hydrogen...

do not form octets

boron bonds:

6

beryllium bonds:

4

Hydrogen bonds:

2

What is the VSEPR theory?

A system of modeling molecules based around electron domains and how they orient themselves.

VSEPR acronym

Valence Shell Electron Pair Repulsion (theory)

what is an electron domain?

region around central atom with the valence electrons

how do valence electrons change molecule shape?

electrons repell each other

How do you describe molecule shape?

electron and molecular geometry

wedge

coming forward

dash

going back

lone pairs vs bonds

lone pairs have more repulsion than bonds

ionization energy trend

increases up and to the right

electronegativity trend

increases up and to the right

atomic radius trend

increases down and to the left

electron affinity trend

increases to the right and up

electron affinity

the energy needed to remove an electron from a negative ion to form a neutral atom or molecule

electronegativity why?

more protons pull for electrons because less rings more pull

atomic radius why?

more orbitals and protons around nucleus

ionization energy

The amount of energy required to remove an electron from an atom

ionization energy why?

more pull because shells are loser to the nucleus and have more protons

partial charges

more electronegative atoms have partial negative charge, less electronegative atoms have partial positive charge

formal charges

the charge an atom would have if all the electrons in bonds were shared equally

how to find formal charges

To find formal charges in a Lewis structure, for each atom, you should count how many electrons it "owns". Count all of its lone pair electrons, and half of its bonding electrons. The difference between the atom's number of valence electrons and the number it owns is the formal charge