AoS 1

Question 1

what is an element?

Answer 1

an element is a substance that is made up of only one type of atom, can’t be broken down into simpler substances.

Question 2

what does the atomic number and mass number of an atom tell us?

Answer 2

atomic number - number of electrons
mass number - the sum of the number of protons and neutrons

Question 3

what is the octet rule?

Answer 3

the tendency of atoms to want to have 8 electrons in their outer (valence) shell.

Question 4

what is an isotope?

Answer 4

an isotope is an element that has the same number of protons but a different number of neutrons, altering it’s mass. Eg, helium - 4

Question 5

what is metallic bonding?

Answer 5

The electrostatic attraction between metal cations and the sea of delocalised electrons.

Question 6

properties of metals

Answer 6

lustrous, malleable, ductile, can conduct electricity and heat, and most have a high melting and boiling point

Question 7

malleability explanation

Answer 7

metals are malleable because force can be applied and they can be bent into shapes because the sea of electrons moves with the cations, maintaining the strong bond.

Question 8

ductility explanation

Answer 8

metals can be drawn into wires without breaking because they are malleable and can be pulled into a single layer of cations.

Question 9

electrical conductivity explanation

Answer 9

electricity in metals is the flow of electrons, because the sea of electrons can move freely across the lattice, they can carry a charge across it.

Question 10

heat conductivity explanation

Answer 10

the metal absorbs heat and the rise in temperature causes an increase of kinetic energy of the cations and delocalised electrons. they begin to vibrate, and the vibrations transfer the energy to the nearby cations and the heat is carried across the metal. this is a chain reaction.

Question 11

high melting/boiling point (most)

Answer 11

most metals have a high melting and boiling point because the bond between the cations and delocalised electrons is very strong, so a lot of heat energy is required to break the bond.

Question 12

lustrous explanation

Answer 12

metals are lustrous because the sea of delocalised electrons reflect light.

Question 13

ionic bonding

Answer 13

when metal atoms donate their valence electrons to non-metal atoms, forming cations and anions. The positive cations and negative anions are attracted to each other forming an electrostatic bond.

Question 14

properties of ionic compounds

Answer 14

form an ionic crystal lattice, conduct electricity in molten and aquaeous solutions, brittle, hard, high melting and boiling point.

Question 15

conduct electricity in an aquaeous/molten solution explanation

Answer 15

in a solution or in a molten state, the cations and anions are able to freely move so they are able to carry a charge. as a solid, the ions are stuck in the lattice and cannot move, so they cannot carry a charge.

Question 16

ionic lattice explanation

Answer 16

they are arranged in a regular pattern, this maximises the attraction between the oppositely charged ions and and minimises the repulsion between ions with like charges.

Question 17

brittle and hard explanation

Answer 17

ionic compounds are hard, this is because the electrostatic bond between the anions and cations is very strong. they are also brittle, because when enough force is applied, instead of the unlike charges being lined up, the like charges line up and they repel each other, breaking the lattice.

Question 18

polyatomic ions

Answer 18

ions made up of more than one atom, and they have a charge. examples: iron (II), iron (III), OH- (hydroxide), NO3 - (nitrate), SO4 2- (sulfate), PO4 3- (phosphate)

Question 19

what do groups and periods indicate?

Answer 19

elements in the same group (up & down) have the same number of electrons in their valence shell, elements in the same period (left & right) have the same number of electron shells.

Question 20

electron shell rule

Answer 20

2n^2, but outer shell can only have 8.