atoms & periodic table

Question 1

what is an atom

Answer 1

chemical building blocks of the world
- made of electrons protons and neutrons

Question 2

what is an element

Answer 2

a pure substance containing 2 or more of the same atom

Question 3

what is a compound

Answer 3

2 or more atoms of different elements chemically bonded together

Question 4

what is the law of conservation of mass

Answer 4

mass is neither created or destroyed in an equation so the total mass of the product should be the same as the total mass of the reactants. (why we balance)

Question 5

filtration method

Answer 5

separating insoluble from solution
1. put filter paper in a funnel and place it in a test tube
2. pour solution into filter paper
3. solvent will be in the test tube, insoluble solid will remain in the filter paper

Question 6

crystallisation method

Answer 6

when soluble need to be separated
1. heat up solution on evaporating basin
2. keep heating until most solvent has evaporated
3. remove from heat and leave near a window for a few days
4. once liquid has completely evaporated pat crystals dry with filter paper/ paper towel

Question 7

distillation method

Answer 7

separating a solution made of 2 solvents
1. heat up solution using bunsen burner
2. solvent with lower boiling point will evaporate leaving 1 solvent behind

Question 8

fractional distillation

Answer 8

when 2 liquids are bonded together and need to be separated
1. heat solution with bunsen burner
2. solvent with lower boiling point will evaporate and enter a cooling jacket
3. cools down and condenses again
4. goes into a separate beaker

Question 9

paper chromatography

Answer 9

to separate + identify substances in a solution, compounds in a mixture dissolve at different rates.
- spot of solution is added on a pencil line near bottom of chromatography paper.
- paper is placed in a beaker of a solvent
- paper soaks up the solvent and runs through the added solution
- the further up a solution is on the paper, the more soluble it is in that solvent

Question 10

who created the periodic table (JJD)

Answer 10

John Dalton 1808
John Newlands 1864
Dimitri Mendeleev 1869

Question 11

John Dalton

Answer 11

• arranged the elements in order of weight
• thought elements were tiny spheres that couldn’t be divided

Question 12

John Newlands

Answer 12

• created law of octaves, every 8 elements have similar properties
• table was not grouped

Question 13

Dimitri Mendeleev

Answer 13

• left gaps for undiscovered elements
• swapped some around based on atomic weight

Question 14

JJ Thompson

Answer 14

discovered the electron, made the plum pudding model

Question 15

Rutherford, Geiger and Marsden

Answer 15

alpha particle experiment
- directed alpha particles at sheet of gold foil
- thought particles would all pass through
- some did, some deflected, some bounced back, led to discovery of nucleus

Question 16

Niels Bohr

Answer 16

electrons orbit nucleus at specific distances in fixed energy levels (shells)

Question 17

James Chadwick

Answer 17

proved existence of neutrons within nucleus

Question 18

what is an atomic number

Answer 18

the number of protons and electrons in each atom, always the smaller number

Question 19

what is the atomic mass

Answer 19

the total numbers of protons, neutrons and electrons

Question 20

what is an ion

Answer 20

same number of protons but different amount of electrons

Question 21

what is an isotope

Answer 21

same number of protons but different neutrons

Question 22

the periodic table

Answer 22

the periodic table is an arrangement of elements where they are placed in the order of their atomic number in periods and groups

Question 23

metals and non-metals

Answer 23

• metals tend to have higher boiling and melting points
• ductile (drawn out into wires) and malleable (moulded/ hammered into different shapes without breaking)
• non-metals found in top right (staircase thing)

Question 24

groups

Answer 24

• groups 1,2,3 tend to lose electrons to form ions
  (metals react by losing electrons)
• group 5,6,7 gain electrons to form negative ions
  (non-metals react by gaining electrons)

Question 25

group 0 - noble gases

Answer 25

• have 8 electrons in their outer shells (except helium,2)
• all have full outer shells, so stable & very unreactive
• monatomic
• reactivity decreases
• boiling and melting points increase

Question 26

group 1 properties

Answer 26

• very reactive, stored in oil
• reactivity increases
• boiling and melting points decreases.
• react with water > fizzing, hydrogen gas produced
• 1 electron in outer shell, lose to get positive ion

Question 27

group 7 - halogens

Answer 27

• diatomic molecules (covalent)
• all have 7 electrons in outer shells (has to gain 1 )
• reactivity decreases as you go down
• boiling and melting points increase

Question 28

what happens when the atoms get larger

Answer 28

• it is easier to lose electrons
• it is hard to gain (electrons in outer shell are further away and the attraction from the nucleus is weaker, called shielding)

Question 29

transition elements

Answer 29

all metals (centre block between group 2&3)
- high densities
- high melting and boiling points
- conductors of heat and electricity
- good catalysts

Question 30

what is the particle theory

Answer 30

everything is made up of tiny particles which cant be broken down any further

Question 31

what are catalysts

Answer 31

increases the rate of reaction without being used up themselves