Chapter 6 - Covalent Bonding Flashcards
what is covalent bonding
where 2 atoms share valence electrons in an attempt to satisfy the octet rule.
what is a molecule
a group of atom.
what are diatomic molecules
covalent bonded molecule between two of the same atom
what are electron dot diagrams also called?
lewis diagrams
paired electrons are also called…
lone pairs
unpaired electrons can also be called…
bonding electrons
what is the central atom?
the atom in a molecule that has the most bonding electrons. it is placed in the centre with the other atoms bonded to it.
structural formulas can also be called…
valence diagrams or shape diagrams
define ‘molecular’
relating to or consisting of molecules
steps to naming covalent compounds
- the first elements name is in full
- the second element is named like an anion with the
- ide suffix. - the number of atoms of each is given by a prefix
- if a vowel is between the name and the suffix, it is dropped for better pronunciation
what are non-polar bonds
where the shared electron pair is shared equally between the nuclei of 2 atoms in a uniform distribution.
what are polar bonds
where the shared electron pair is un equally shared and thus is unsymmetrically distributed between the 2 atoms.
steps to determine polarity
- draw a shape diagram
- use the electronegativities to determine poles [starting with the lowest electronegativity]
- use shape and poles to see if molecule is polar. if dipoles don’t cancel or molecule is not symmetrical, it is polar.
what are intermolecular forces
the attraction between molecules of a substance
define dispersion forces
where the nucleus of a neighbouring atom is attracted to the negative instantaneous dipole of another atom. They are weak but accumulate with more electrons.
what affects the strength of dispersion forces
more electrons=stronger
shape that allows molecules to come closer together=stronger
define dipole-dipole attraction
if both molecules a polar, they have permanent dipoles which attract to opposite dipoles of other molecules.
define hydrogen bonding
when hydrogen is bonded to N,O or F. This allows very strong attraction between molecules as the very positive hydrogen can attract negative areas of other molecules
properties of covalent compounds
no electrical conduction (electrical neutral)
low points (weak dispersion)
soft and easily scratched (weak dispersion)
if a covalent compounds has multiple bonds between atoms, its shape is always…
linear
electron dot diagrams
are quick to draw
is not an accurate representation of molecular shape
structural formulas
clearly shows number of covalent bonds in molecule
is not an accurate representation of molecular shape
ball and stick model
shows the shape of the molecule
too complicated to draw
space filling model
shows the relative sizes of atoms
too complicated to draw
why does frozen water float on liquid water?
because the kinetic energy lost as the temperature drops allows more time for hydrogen bonds to form and create a neatly arranged shape. This shape is less dense than the liquid water because as liquid the molecules are constantly moving while still being bonded.
why can water dissolve ionic compounds?
because of its polarity. The negatively charged oxygen atom attracts the cation and the positively charged hydrogens attract the anion, breaking the lattice apart and thus dissolving the substance.
always remember to put….
LONE PAIRS ON DIAGRAMS
