Chapter 5 Flashcards
general terms
compound
a substance that is made up of 2 or more different elements combined together chemically. eg- NaCl
molecule
a group of atoms joined together. the smallest particle of an element or compound that can exist independently. eg- Cl2
octet rule exceptions
- transition metals
- hydrogen, lithium, beryllium tend to achieve 2 electrons in their outer shell rather than 8.
ion
a charged atom or group of atoms
ionic bond
force of attraction between oppositely charged ions in a compound. always formed between the complete transfer of electrons from one atom to another.
charges of ionic compounds
g1- 1+
g2- 2+
g3- 3+
g4- 4+ or 4-
g5- 3-
g6- 2-
g7- 1-
g8- no ion
7 diatomic molecules
hydrogen, nitrogen, fluoride, oxygen, iodine, chloride, bromine
H2, N2, F2, O2, I2, Cl2, Br2
transition metals
element that forms at least one ion with a partially filled sublevel. properties:
-have variable valency
-widely used as compounds
-usually coloured compounds
exceptions to transition metals
Sc3+, Zn2+ because they do not have a partially filled d sub-level
what forms a single bond
when one pair of electrons is being shared between 2 atoms
what forms a double bond
when two pairs of electrons are shared between 2 atoms
what forms a triple bond
when three pairs of electrons are shared between 2 atoms
what shape are all double and triple bonds
linear in shape and single
what are the bond energies for single, double, and triple bonds like
single- weakest
double- stronger than single
triple- strongest
~ this is due to sigma bonds being stronger than pi bonds
sigma bond
formed by the head on overlap of 2 orbitals
pi bond
formed by the sideways overlap of p orbitals
how many sigma and pi bonds in each of the 3 bonds
single bond- one sigma bond
double bond- one sigma bond and one pi bond
triple bond- one sigma bond and 2 pi bonds
properties of ionic bonds
-contains a network of ions in the crystal
-usually hand and brittle
-high melting and boiling points
-usually solid at room temp
-conduct electricity when in molten state or when dissolved in water
properties of covalent bonds
-contain individual molecules
-usually soft
-low melting and boiling points
-usually liquids, gasses or soft solids at room temp
-do not conduct electricity
electronegativity
the relative attraction that an atom in a molecule has for a shared pair of electrons in a covalent bond
uses of electronegativity
- predict polarity of covalent bonds
- predict which compounds are ionic and which are covalent
polar covalent bond
a bond in which there is an unequal sharing of the pair(s) of electrons. this causes one side to be slightly positive and the other slightly negative.
non-polar covalent bond
a bond in which there is an equal sharing of electrons
electronegativity difference greater than 1.7 means
ionic bonding
electronegativity difference less and or equal to 1.7 means
covalent bonding
electronegativity difference between 0.4 and 1.7 means
polar covalent bond
electronegativity difference less than or equal to 0.4 means
non-polar covalent bond
exceptions to predicting bonding in compounds
when the shape of the molecule is:
1. linear
2. trigonal planar
3. tetrahedral
intramolecular bonding
bonding that takes place within a molecule, i.e. holds the atoms together, i.e. ionic and covalent bonding
intermolecular forces
the forces of attraction that exist between molecules, i.e. Van Der Waals forces, dipole-dipole forces, hydrogen bonding
Van Der Waals forces
weak attractive forces between molecules resulting from the formation of temporary dipoles (temporary attraction as a result of a shift of electrons)
~ only force of attraction between non-polar molecules
~boiling point increases with atomic mass
~weakest intermolecular bonding
dipole-dipole forces
forces of attraction between the negative pole of one polar molecule and the positive pole of another polar molecule. a permanent dipole if formed between 2 polar molecules
~medium strength, therefore average boiling point
~higher boiling point than Van der Waals
hydrogen bonds
types of dipole-dipole attraction between molecules in which hydrogen atoms are bonded to nitrogen, oxygen or fluorine.
boiling points
affected by intermolecular bonding and molecular mass. if same intermolecular bonding, the larger molecular mass will have the higher boiling point
solubility
affected by intramolecular bonding. like dissolves like. water= polar, oil= non-polar
