Fundamental Chemistry

Question 1

charges

Answer 1

neutrons- neutral
protons- positive
electrons- negative

Question 2

elemental composition

Answer 2

top number= atomic number- protons
bottom number= atomic mass- protons + neutrons

Question 3

isotope

Answer 3

element with the same number of protons and a different number of neutrons
changes atomic mass
same chemical characteristics

Question 4

radioisotopes

Answer 4

isotopes that are radioactive
14C can be used to determine age of artefacts
measures decay of 14C using half life

Question 5

isotopes- anti doping

Answer 5

differences in levels of metabolised testosterone can be measured
(listen to recording)

Question 6

atom- electrons

Answer 6

electrons are found in orbitals
held in place by electrostatic attractions
electron shells fill sequentially

Question 7

octet rule

Answer 7

confused - listen to recording

Question 8

molecules

Answer 8

atoms are stable when their outer shell is full of electrons
atoms can gain (-ve) or lose (+ve) electrons to gain full outer shell
atoms can join with other atoms to form molecules known as bonding

Question 9

chemical bonds

Answer 9

can be formed by sharing or transferring electrons
ionic- electron transfer
bond forms between metal and non metal eg NaCl
covalent - electron sharing
bond forms between non metals eg H2O
metallic- share a sea of delocalised electrons between metals

Question 10

ionic bonding/ compounds- properties

Answer 10

high melting and boiling point- strong intermolecular forces (hard to break bonds)
soluble in water- highly polar
conduct electricity when in molten or aqueous solutions
brittle- form lattice structure

Question 11

covalent bonding - properties

Answer 11

valency refers to the number of covalent bonds an atom can produce
low melting point and boiling point - weak intermolecular forces (volatile)
low solubility in water- low polarity
do not conduct electricity
can form double/ triple covalent bonds

Question 12

metallic bonding

Answer 12

lattice made up of metal ions fixed in position
surrounded by sea of delocalised electrons
when voltage is applied, electrons move from high to low potential, forming current
conduct electricity due to free moving electrons
malleable (into sheets) and ductile (pulled into wires)

Question 13

shapes of molecules

Answer 13

shape of molecule influences chemical behaviour
shape of covalent molecule depends on number of electron pairs in outer shell
electron pairs exist in a charge cloud
clouds repel eachother

Question 14

polarisation

Answer 14

different atoms have different levels of electronegativity
more electronegative will attract shared electron pairs towards them
creates polar bond where electrongetaive atoms becomes -ve charge
atoms of similar electronegativity do not form polar bonds

Question 15

electronegativity

Answer 15

measure of the ability of an atom that is bonded to another atom to attract electrons to itself

Question 16

bond polarity

Answer 16

polarity can be shown by labelling the end of being partially +ve or partially -ve charged
non polar covalent= E<0.5 (eg ClCl)
polar covalent= >0.5 E < 2 (eg HCl)
ionic E>2 (eg NaCl)

Question 17

polarisation importance

Answer 17

polar molecules are more soluble in water
steroid hormones are non polar and are not easily dissolved in blood/ urine
polarity determines its ability to transport in/ out of cells

Question 18

intermolecular forces

Answer 18

between molecules (covalent is intramolecular, within molecule)
weaker than bonds between atoms
stronger IMF, more energy required to break molecules apart
gases- weak IMF
liquid/solid - strong IMF

Question 19

london dispersion forces

Answer 19

atoms and molecules exhibit LDF between themselves
electrons orbiting nuclear create a cloud of neg charge
large molecules have large electron clouds + strong LD interactions
stronger LDF= higher boiling point

Question 20

dipole dipole attractions

Answer 20

permanent dipoles eg HCl are in permanent state of polarisation + attract each other
eg HCl will attract HCl
eg hydrogen bonds (H covalently bonded to flourine, nitrogen or oxygen) are strong dipole dipole attraction

Question 21

intermolecular forces- ionic

Answer 21

ionic compunds transfer electrons so atoms are permanently charged
attracts atoms togther and forms large lattices structures
bonds are very strong= high boiling point
in solution the atoms dissociate (separate) + remain in their individual charged atom state

Question 22

ionic bonding

Question 23

hydroxyl groups

Answer 23

oxygen bonded to hydrogen and organic molecule eg carbon
R group= carbon chains
polar bond between O and H and O and R
also called alcohols
-OH

Question 24

amine groups

Answer 24

amine functional groups contain a nitrogen atom with a lone pair of electrons
class of amine depends what else it is bonded to
amino acid contain primary amine group- NH2 and R group
secondary amine= NH and 2 R group
tertiary amine= N and 3 R group

Question 25

carboxyl group

Answer 25

carbon atom is double bonded to oxygen and 2 side chains

Question 26

pH

Answer 26

used to describe acidity/ alkalinity of a solution
related to conc of H+ ions
greater conc of H+ = more acidic
measured on log scale from 1 to 14

Question 27

moles

Answer 27

mole= avogadros constant = 6.02x10^23
1 mole = 6.02x10^23

Question 28

molar concentration

Answer 28

refers to number of moles of a substance in a defined volume
1 mole of a molecule is always its molecular weight in gram
mass= molecular weight x moles