Atoms, elements and compounds

Question 1

Relative charges and approximate relative masses of protons, neutrons and electrons

Answer 1

Protons:
-Charge: +1
-Mass: 1
Neutron: 
-Charge: 0
Mass: 1
Electron: 
Charge: -1
Mass: 1/1836

Question 2

proton number

Answer 2

(atomic number), the number of protons in the nucleus of an atom

Question 3

nucleon number

Answer 3

(mass number), the total number of protons and neutrons in the nucleus of an atom

Question 4

Electron Number

Answer 4

is the Atomic number

Question 5

Elements​ ​in​ ​the​ ​same​ ​periodic​ ​group​ ​have​ ​the​ ​same:

Answer 5

Elements​ ​in​ ​the​ ​same​ ​periodic​ ​group​ ​have​ ​the​ ​same​ ​amount​ ​of​ ​electrons​ ​in​ ​their outer​ ​shell,​ ​which​ ​gives​ ​them​ ​similar​ ​chemical​ ​properties.

Question 6

Isotopes

Answer 6

atoms of the same element which have the same proton number but a different nucleon number

Question 7

Why do isotopes have the same properties

Answer 7

isotopes have the same properties because they have the same number of electrons in their outer shell

Question 8

two types of isotopes

Answer 8

radioactive and non-radioactive

Question 9

Medical and industrial use of radioactive isotopes

Answer 9

Medical​ ​uses:
-Sterilising​ ​equipment, Tracers
Industrial​ ​uses:
-Smoke​ ​alarms, Tracers

Question 10

differences between elements, mixtures and compounds, and between metals and non-metals

Answer 10

-Element​ ​=​ ​substance​ ​made​ ​from​ ​only​ ​one​ ​type​ ​of​ ​atom
-Compound​ ​=​ ​substance​ ​made​ ​from​ ​two​ ​or​ ​more​ ​elements​ ​that​ ​have​ ​reacted chemically​ ​with​ ​each​ ​other
-A​ ​mixture: Consists​ ​of​ ​2​ ​or​ ​more​ ​elements​ ​or​ ​compounds​ ​not​ ​chemically​ ​combined
together
-Metals​ ​=​ ​elements​ ​that​ ​react​ ​to​ ​form​ ​positive​ ​ions. ​they​ ​lose electron(s)​ ​in​ ​order​ ​to​ ​form​ ​these​ ​positive​ ​ions
-Non-metals​ ​=​ ​elements​ ​that​ ​do​ ​not​ ​form​ ​positive​ ​ions. They​ ​gain
electron(s)​ ​in​ ​order​ ​to​ ​form​ ​these​ ​negative​ ​ions

Question 11

What is an alloy, such as brass

Answer 11

-it is a mixture of metal with other elements.
-alloys​ ​are​ ​harder​ ​than​ ​pure​ ​metals​ ​because:
In​ ​a​ ​pure​ ​metal,​ ​all​ ​the​ ​+​ ​ions​ ​are​ ​the​ ​same​ ​size and​ ​in​ ​a​ ​regular​ ​arrangement​ ​so​ ​can​ ​easily​ ​slide over​ ​each​ ​other
In​ ​an​ ​alloy,​ ​there​ ​are​ ​+​ ​ions​ ​from​ ​different metals,​ ​meaning​ ​they​ ​are​ ​different​ ​sizes,​ ​which disrupts​ ​the​ ​regular​ ​arrangement​ ​and​ ​prevents the​ ​layers​ ​from​ ​sliding​ ​as​ ​easily

Question 12

formation of ions by electron loss or gain

Answer 12

if​ ​an​ ​atom​ ​gains​ ​electrons,​ ​it​ ​becomes​ ​a​ ​negative​ ​ion
if​ ​an​ ​atom​ ​loses​ ​electrons,​ ​it​ ​becomes​ ​a​ ​positive​ ​ion
o Cation​ ​=​ ​positive​ ​ion​
o Anion​ ​=​ ​negative​ ​ion​

Question 13

formation of ionic bonds between metallic and non-metallic elements

Answer 13

• Metal​ ​atoms​ ​lose​ ​electrons​ ​to​ ​become​ ​positively​ ​charged​ ​ions
• Non-metal​ ​atoms​ ​gain​ ​electrons​ ​to​ ​become​ ​negatively​ ​charged​ ​ions

Question 14

formation of ionic bonds between elements from Groups I and VII

Answer 14

• group​ ​1​ ​atom​ ​loses​ ​one​ ​electron​ ​and​ ​forms​ ​a​ ​+1​ ​ion
• group​ ​7​ ​atom​ ​gains​ ​the​ ​electron​ ​the​ ​group​ ​1​ ​atom​ ​lost​ ​and​ ​becomes​ ​a​ ​-1 ion

Question 15

the lattice structure of ionic compounds as a regular arrangement of alternating positive and negative ions

Answer 15

Held​ ​together​ ​by​ ​strong​ ​electrostatic​ ​forces​ ​of​ ​attraction​ ​between​ ​oppositely charged​ ​ions,​ ​which​ ​are​ ​regularly​ ​arranged

Question 16

differences in volatility, solubility and electrical conductivity between ionic and covalent compounds

Answer 16

-Covalent​ ​compounds:​ ​giant​ ​covalent​ ​structures​ ​have​ ​high​ ​melting/boiling
points​ ​and​ ​so​ ​low​ ​volatility.​ ​Simple​ ​molecular​ ​covalent​ ​substances​ ​have
low​ ​melting/boiling​ ​points​ ​so​ ​have​ ​high​ ​volatility
-Ionic​ ​compounds:​ ​compounds​ ​have​ ​high​ ​melting​ ​and​ ​boiling​ ​points​ ​(low volatility)
Solubility:
○ Ionic​ ​substances
tend​ ​to​ ​be​ ​soluble​ ​in​ ​water,​ ​but​ ​insoluble​ ​in​ ​other​ ​covalently bonded​ ​solvents​ ​e.g.​ ​ethanol​ ​or​ ​propanone
Covalent​ ​substances
Opposite​ ​of​ ​ionic​ ​substances​ ​in​ ​terms​ ​of​ ​solubility
Soluble​ ​in​ ​covalent​ ​type​ ​solvents
Insoluble​ ​in​ ​water

Electrical​ ​conductivity:
Covalent​ ​compounds​ ​do​ ​not​ ​conduct​ ​electricity​ ​–​ ​they​ ​have​ ​no​ ​free flowing​ ​particles​ ​able​ ​to​ ​carry​ ​charge​ ​(except​ ​for​ ​graphite)
Ionic​ ​compounds​ ​conduct​ ​electricity​ ​ONLY​ ​when​ ​molten​ ​or​ ​dissolved​ ​in aqueous​ ​solution,​ ​because​ ​then​ ​the​ ​ions​ ​are​ ​able​ ​to​ ​move​ ​and​ ​carry charge,​ ​conducting​ ​electricity​ ​-​ ​when​ ​solid,​ ​the​ ​ions​ ​are​ ​fixed

Question 17

differences in melting point and boiling point of ionic and covalent compounds in terms of attractive forces

Answer 17

○ Covalent​ ​compounds:
■ Substances​ ​that​ ​consist​ ​of​ ​giant​ ​covalent​ ​structures​ ​are​ ​solids​ ​with​ ​very
high​ ​melting​ ​points.​ ​All​ ​of​ ​the​ ​atoms​ ​in​ ​these​ ​structures​ ​are​ ​linked​ ​to other​ ​atoms​ ​by​ ​strong​ ​covalent​ ​bonds,​ ​which​ ​must​ ​be​ ​overcome​ ​to​ ​melt or​ ​boil​ ​these​ ​substances.
■ Substances​ ​that​ ​consist​ ​of​ ​small​ ​molecules​ ​are​ ​usually​ ​gases​ ​or​ ​liquids that​ ​have​ ​low​ ​boiling​ ​and​ ​melting​ ​points.They​ ​have​ ​weak​ ​intermolecular forces​ ​between​ ​the​ ​molecules.​ ​These​ ​are​ ​broken​ ​in​ ​boiling​ ​or​ ​melting,​ ​not the​ ​covalent​ ​bonds.
○ Ionic​ ​compounds:
■ Strong​ ​electrostatic​ ​forces​ ​of​ ​attraction​ ​between​ ​oppositely​ ​charged​ ​ions
■ Requires​ ​a​ ​lot​ ​of​ ​energy​ ​to​ ​overcome​ ​these​ ​forces​ ​of​ ​attraction
■ Therefore,​ ​the​ ​compounds​ ​have​ ​high​ ​melting​ ​and​ ​boiling​ ​points

Question 18

giant covalent structures of graphite and diamond

Answer 18

Diamond
​each​ ​carbon​ ​is​ ​joined​ ​to​ ​4​ ​other​ ​carbons
covalently.
-It’s​ ​very​ ​hard,​ ​has​ ​a​ ​very​ ​high​ ​melting​ ​point​ ​and​ ​does​ ​not
conduct​ ​electricity.
Graphite
In​ ​graphite,​ ​each​ ​carbon​ ​is​ ​covalently​ ​bonded​ ​to​ ​3​ ​other​ ​carbons,​ ​forming​ ​layers
of​ ​hexagonal​ ​rings,​ ​which​ ​have​ ​no​ ​covalent​ ​bonds​ ​between​ ​the​ ​layers.
o The​ ​layers​ ​can​ ​slide​ ​over​ ​each​ ​other​ ​due​ ​to​ ​no​ ​covalent​ ​bonds​ ​between
the​ ​layers,​ ​but​ ​weak​ ​intermolecular​ ​forces.​ ​Meaning​ ​that​ ​graphite​ ​is​ ​soft
and​ ​slippery.

Question 19

macromolecular structure of silicon(IV) oxide (silicon dioxide)

Answer 19

Each​ ​silicon​ ​atom​ ​is​ ​covalently​ ​bonded​ ​to​ ​4​ ​oxygen​ ​atoms
Each​ ​oxygen​ ​atom​ ​is​ ​covalently​ ​bonded​ ​to​ ​2​ ​silicon​ ​atoms, Therefore,​​the ​​formula​​ is​​ SiO​2

Question 20

Relate their structures to their uses, e.g. graphite as a lubricant and a conductor, and diamond in cutting tools

Answer 20

Graphite
-Lubricant​ ​–​ ​layers​ ​slide​ ​over​ ​each​ ​other
-Conductor​ ​–​ ​can​ ​conduct​ ​electricity
Diamond
-Cutting​ ​tools​ ​–​ ​very​ ​hard​ ​due​ ​to​ ​rigid​ ​structure

Question 21

the similarity in properties between diamond and silicon(IV) oxide, related to their structures

Answer 21

Similar​ ​properties:
-Very​ ​hard
-Very​ ​high​ ​melting​ ​and​ ​boiling​ ​points
-Insoluble​ ​in​ ​water
-Does​ ​not​ ​conduct​ ​electricity
These​ ​are​ ​due​ ​to​ ​the​ ​strong​ ​covalent​ ​bonds​ ​that​ ​hold​ ​the​ ​atoms​ ​in​ ​a​ ​rigid structure

Question 22

metallic bonding

Answer 22

lattice of positive ions in a ​sea​ ​of delocalised​ ​electrons

Question 23

describe the electrical conductivity and malleability of metals

Answer 23

• Metals​ ​consist​ ​of​ ​giant​ ​structures​ ​of​ ​atoms​ ​arranged​ ​in​ ​a​ ​regular​ ​pattern.
• The​ ​electrons​ ​in​ ​the​ ​outer​ ​shell​ ​of​ ​metal​ ​atoms​ ​are​ ​delocalised​ ​and​ ​so​ ​are​ ​free​ ​to move​ ​through​ ​the​ ​whole​ ​structure.
• The​ ​sharing​ ​of​ ​delocalised​ ​electrons​ ​gives​ ​rise​ ​to​ ​strong​ ​metallic​ ​bonds
• electrical​ ​conductivity:​ ​metals​ ​can​ ​conduct​ ​electricity​ ​because​ ​the​ ​sea​ ​of delocalised​ ​electrons​ ​is​ ​able​ ​to​ ​move
• malleability:​ ​the​ ​regular​ ​arrangement​ ​of​ ​equally​ ​sized​ ​metal​ ​ions​ ​means​ ​that​ ​the layers​ ​of​ ​ions​ ​are​ ​able​ ​to​ ​slide​ ​over​ ​each​ ​other​ ​easily,without​ ​the​ ​metal shattering,​ ​​ ​making​ ​metals​ ​malleable