Outcome 1

Question 1

what is an atomic emission spectrum?

Answer 1

by passing the light of an element through a prism it produces an atomic emission spectrum for that element

Question 2

who is given credit for the periodic table we see today?

Answer 2

dmitri mendeleev

Question 3

how many elements in the periodic table?

Answer 3

118 known elements

Question 4

what do elements in the same group and period have in common?

Answer 4

group- similair chemical properties i.e. same number valence of electrons
period- have same number of atomic orbitals

Question 5

what is the oxidising strength of electrons?

Answer 5

how readily an atom gains electrons

Question 6

what is the reducing strength of electrons?

Answer 6

how readily an atom loses electrons

Question 7

how can the trends of atomic size be determined?

Answer 7

going across a period it decreases

going down a group it increases

Question 8

how can the trends of metallic character be determined?

Answer 8

going across a period it decreases

going down a group it increases

Question 9

how can the trends of reactivity be determined?

Answer 9

going across a period it decreases

going down a group it increases

Question 10

how can the trends of electronegativity be determined?

Answer 10

going a period across it increases

going down a group it decreases

Question 11

how can the trends of oxidising strength be determined?

Answer 11

going across a period it increases

going down a group it decreases

Question 12

how can the trends of reducing strength be determined?

Answer 12

going across a period it decreases

going down a period it increases

Question 13

what is ionisation energy?

Answer 13

the energy required to remove an electron from a gaseous atom

Question 14

how can the trends of ionisation energy be determined?

Answer 14

going across a period it increases

going down a group it decreases

Question 15

what is an ionic bond?

Answer 15

when two atoms gain or lose electrons to form an ionic lattice held together via electrostatic attraction

Question 16

what is the structure of an ionic lattice?

Answer 16

• held together via electrostatic attraction
• each cation is surrounded by anions and vise-versa
• the relative size and numbers of ions present determine the ‘actual’ lattice structure

Question 17

properties of ionic compounds with relation to structure

Answer 17

• usually crystalline solids, due to the 3D patterns of the lattice
• have high melting + boiling points, due to the large amount of energy needed to separate ions
• do not conduct electricity in the solid form, due to the fixed particles
• are hard, due to the strong ionic bonds in the lattice
• often dissolve in water, as water molecules are able to move between ions and free them by disrupting the crystal structure
• are brittle, repulsion between like charges shatters the crystal
• in the molten form ions are able to slide past on another and can therefore conduct electricity

Question 18

uses of ionic compounds

Answer 18

sodium hydrogen carbonate- an enviro friendly cleaning agent
ammonium nitrate- used to manufacture explosives and fertilisers
nitrate, nitrite + sulfite- used to preserve food

Question 19

why is copper so widely used?

Answer 19

low melting point and the ease in which it could be extracted from its ore

Question 20

why has aluminium only recently become popular?

Answer 20

was difficult to extract from its ore despite being extremely abundant

Question 21

properties of metals

Answer 21

• lustrous (due to the mobile electrons being able to reflect light)
• ductile + malleable (layers of atoms can move past one another without disrupting the force between the cations and delocalized electrons)
• good conductor of heat (the bumping of the electrons transfers heat) + electricity (the movement of the delocalized e- form an electric current)
• often hard
• generally have high density (metallic ions are closely packed within the lattice)

Question 22

substitutional alloy vs interstitial alloy

Answer 22

s- if the atoms of the metals are about the same size they can replace each other in the metal crystals
i- if they sizes differ greatly the smaller atoms may fit into the spaces between the larger atoms

Question 23

give 2 examples of alloys and their composition

Answer 23

stainless steel- 73% Fe, 18% Cr, 9% Ni

sterling silver- 92.5% Ag, 7.5% Cu

Question 24

what is work hardening?

Answer 24

bending or hammering cold metals causes their crystal grains to become smaller therefore bending becomes more difficult

Question 25

difference between annealing, quenching and tempering a metal?

Answer 25

a- heated until red hot, cooled slowly, larger crystals are formed so the metal becomes softer, used to restore ductility
q- heated until red hot, cooled in water, smaller crystals formed, harder and more brittle metal formed
t- quenched metals reheated, cooled slowly, reduces brittleness, remains hard

Question 26

what doesn’t the lattice model tell us about properties?

Answer 26

magnetism + strength

Question 27

metal strength is explained by what model?

Answer 27

ball bearing model

• when a metal bends, layers of atoms slide over each over
• easier they slide=easier the metal bends
• metals w/ larger grains have fewer dislocations=bend easier
• metals w/ small grains have more dislocations=do not bend as easily
• grains are the areas of close packed metals