key concepts

Question 1

History of the atom?

Answer 1

Dalton: Said that there was atoms and imagined them as tiny spheres that couldn’t be divided any further

JJ Thompson: Discovered electron/ came up with plum pudding

Rutherford: proved Thompson’s wrong with (gold) alpha particle scattering experiment

Nils Bohr: said electrons go in shells

Mendeleev: arranged the elements in order and developed the modern periodic table. He was clever because he left gaps for undiscovered elements that he knew were going to be discovered

Question 2

Water?

Answer 2

H2O

Question 3

Carbon dioxide?

Answer 3

CO2

Question 4

Chlorine?

Answer 4

Cl2

Question 5

Ammonia?

Answer 5

NH3

Question 6

Hydrogen?

Answer 6

H2

Question 7

Oxygen?

Answer 7

O2

Question 8

Ammonium

Answer 8

NH4 ⁺

Question 9

Nitrate?

Answer 9

NO₃ -

Question 10

Sulfate?

Answer 10

SO4 ² ⁻

Question 11

Hydroxide?

Answer 11

OH -

Question 12

Carbonate?

Answer 12

CO3 ² ⁻

Question 13

How to work out relative mass? (isotopes)

Answer 13

Times mass the numbers by percentages and then add them together. then divide this by 100

eg with O-17 (70%) and O-16 (30%)

(70 x 17) + (30 x 16)

          /100

Question 14

difference between a molecule and a compound?

Answer 14

a molecule is more than 1 atom bonded

a compound is two different atoms bonded

all compounds are molecules but not all molecules are compounds

Question 15

Hazard symbols

Answer 15

(yet to make a flashcard)

Question 16

Ionic bonding basics?

Answer 16

Ion - an atom that has lost or gained electrons giving it a charge.

Metals lose electrons (to get a full outer shell) becoming positive - cations

Non - metals gain electrons (to get a full outer shell) becoming negative - anions

These Ions are then attracted to each other because of electrostatic forces. (opposites attract)

Question 17

Ionic compound properties

Answer 17

• They all have a giant ionic lattice structure. strong charges between oppositely charged ions in all directions
• high melting point and boiling points due to strong attractions
• solid compounds can’t conduct electricity because the ions aren’t free to move
• they can conduct electricity when molten or dissolved because the ions are free to move

Question 18

Covalent bonding basics

Answer 18

• A covalent bond is when atoms share electrons
• it is done by non metals
• they can either share one pair or two pairs of electrons

Question 19

properties of covalent simple molecular substances

Answer 19

examples of simple Molecular substances : water, hydrogen, HCl, oxygen, methane , carbon dioxide.

• substance with covalent bonds usually have simple molecular structures.
• atom within the molecules held together by very strong covalent bonds but forces between the molecules are very weak
• low melting and boiling point because of weak forces between the molecules
• most are gases and liquids and room temp
• as they get bigger forces between molecules increase, increasing mp & bp
• Molecular compounds conduct electricity as they don’t contain free electrons or ions.

Question 20

properties of giant covalent structures

Answer 20

a