Chemical Bonding: Chemical Formulas

Front 1

what is the octet rule?

Back 1

when bonding, atoms tend to reach an electron arrangement with 8 electrons in outer shell.
exceptions are: transition metals, gases near helium (have 2 in outer shell)

Front 2

what is an ionic bond?

Back 2

the force of attraction between oppositely charged ions in a compound

Front 3

what is a transition metal?

Back 3

an element that forms at least one ion with a partially filled d-sublevel

Front 4

why are Sc and Zn not part of the transition metals?

Back 4

Sc and Zn...
do not have a variable valency
produce white compounds
not used as catalysts

Front 5

what is a molecule?

Back 5

a group of atoms joined together. it is the smallest part of an element or compound that can exist independently

Front 6

what is a covalent bond?

Back 6

the chemical bond formed by sharing a pair of electrons

Front 7

using the valence shell electron pair repulsion theory to determine the shape of the molecule

Back 7

-determine what the central atom is
-use periodic table to determine no. of bond pairs
-the group the element is in will determine e- in outer orbit
-subtract no. bond pairs leaving lone electrons

Front 8

define electronegativity

Back 8

the relative attraction an atom in a molecule has for a shared pair of electrons in a covalent bond. delta indicates slightly + or -
measured by Pauling. It is the measure of the amount of energy needed to break a bond

Front 9

what is intramolecular bonding?

Back 9

bonding between 2 atoms within a molecule/particle
ie. ionic bond, covalent bond (polar, weakly polar, non-polar)

Front 10

what is intermolecular bonding?

Back 10

bonding between molecules
eg, Van der Waals forces
dipole-dipole forces
hydrogen bonding

Front 11

how to find if compound is ionic or covalent using electronegativity values

Back 11

if difference is > 1.7 then ionic
if < 1.7 then covalent

Front 12

what is the valency of an element?

Back 12

the number of atoms of Hydrogen (a monovalent element) which will bond with an atom of that electron

Front 13

shapes of molecules
no. of bond pairs=1
no. of lone pairs= N/A

Back 13

linear
AB
180'

Front 14

shapes of molecules
no. of bond pairs=2
no. of lone pairs=0

Back 14

linear
AB2
180'

Front 15

shapes of molecules
no of bond pairs=3
no. of lone pairs=0

Back 15

triangular planar
AB3
120'

Front 16

shapes of molecules
no. of bond pairs=4
no. of lone pairs=0

Back 16

tetrahedral
AB4
109.5'

Front 17

shapes of molecules
no. of bond pairs=3
no. of lone pairs=1

Back 17

pyramidal
AB3
107'

Front 18

shape of molecules
no. of bond pairs=2
no. of lone pairs=2

Back 18

v-shaped
AB2
104.5'

Front 19

explain van der waals forces

Back 19

exist between non-polar molecules. week forces of attraction. formed due to temporary dipoles being formed as moving electrons are momentarily at one end of the molecule

Front 20

explain dipole-dipole forces

Back 20

forces of attraction which exist between the negative pole of one molecule and the positive pole of another. stronger than van der waals

Front 21

explain hydrogen bonds

Back 21

special dipole-dipole forces that exist when hydrogen bonds with nitrogen, oxygen, or fluorine. the strong positive charge on the hydrogen acts as a bridge between the two electronegative atoms

Front 22

melting and boiling points of ionic compounds

Back 22

usually solids at room temperature. very high melting and boiling points caused by the very strong forces of attraction between oppositely charged ions

Front 23

melting and boiling points of covalent compounds

Back 23

depends on two aspects
-the intermolecular forces (eg van der waals)
-the relative atomic mass (Mr) of the compound