CC3 - atomic structure

Question 1

what are atoms

Answer 1

miniscule particles of matter that make up everything in the universe

Question 2

John Dalton

Answer 2

• early 19th century
• described atoms as solid spheres
• atoms cant be broken down into anything simpler
• atoms of same element are identical

Question 3

why did Daltons idea about atoms change

Answer 3

discovery of subatomic particles disproved his idea

Question 4

what are the subatomic particles

Answer 4

• protons
• neutrons
• electrons

Question 5

nucleus of an atom

Answer 5

• found in the centre of the atom
• contains protons and neutrons
• positivley charged (because protons)

Question 6

electrons

Answer 6

• orbit the nucleus in electron shells
• negativley charged
• size of shells determines size of atom

Question 7

how are atoms of different elements different

Answer 7

• all atoms of the same element have a unique atomic number (no. protons)
• no two elements have the same atomic number

Question 8

charges of subatomic particles

Answer 8

proton: +1
neutron: 0
electron: -1

Question 9

relative mass of subatomic particles

Answer 9

proton: 1
neutron: 1
electron: negligable (almost 0)

Question 10

why do atoms have no overall charge

Answer 10

• have the same no. protons as electrons

- opposite charges cancel out

Question 11

size of atom compared to nucleus

Answer 11

compared to atom, nucleus is tiny, most size comes fromo electron shells

Question 12

where is most of the mass of an atom concentrated

Answer 12

in nucleus

Question 13

atomic number

Answer 13

• smaller number of the nuclear symbol

- shows how many protons an element has (every atom of element will ahve same)

Question 14

mass number

Answer 14

• larger number on nuclear symbol

- total number of protons and neutrons together

Question 15

how can number of neutrons be found

Answer 15

mass number - atomic number

Question 16

how can number electrons be found

Answer 16

• neutral electron there is same number of protons and electrons so…
• electrons = atomic number

Question 17

what is an iscotope

Answer 17

• atoms of an element that have the same number of protons, but different numbers of neutrons
• (same atomic no. diff mass no.)

Question 18

what is relative atomic mass

Answer 18

• weighted average of the relative atomic masses of the isotopes in the element
• have the symbol Ar

Question 19

relative atomic mass vs mass number

Answer 19

• mass numbers always whole numbers (not possible to have part of a proton or neutron)
• relative atomic masses are often rounded to the nearest whole number, but arent actually whole numbers

Question 20

element with only 1 iscotop

Answer 20

realtive atomic mass will be same as mass number

Question 21

how to calculate relative atomic mass from iscotopes

Answer 21

[(% of isotope 1 x mass of isotope 1) + (% of isotope 2 x mass of isotope 2)]
/ 100

Question 22

Mendeleev (3)

Answer 22

• sorted elements in order of increasing relative atomic mass
• noticed a pattern in chemical properties
• arranged the elements by putting those with similar properties in groups (columns)

Question 23

what did mendeleev predict

Answer 23

• where missing elements could go and their properties

Question 24

why did mendeleev switch Iodine and Tellurium

Answer 24

were in the wrong group for their behaviour

switched order of a few elements to keep groups consistant

Question 25

what are elements of the periodic table ordered by today

Answer 25

atomic number

Question 26

what do groups show

Answer 26

(columns) number of electron in outer shell

eg. group 1, 1 electron in outer shell

Question 27

exeption to groups and outer shells

Answer 27

group 0, have a full outer shell

Question 28

what do periods show (rows)

Answer 28

number of shells an element has

eg. lithium is in 2nd period, has 2 shells

Question 29

where are metals found on periodic table

Answer 29

left hand side

Question 30

where are non-metals found on periodic table

Answer 30

right hand side in a zig-zag line under boron, around aluminium