2.1.1: Atomic structure and isotopes

Question 1

What is the relative mass of an electron ?

Answer 1

1/2000

Question 1

Give the order of people in the history of the atom

Answer 1

• Dalton
• Thompson
• Rutherford
• Bohr
• Chadwick

Question 2

What did Dalton discover ?

Answer 2

Atoms are indivisible spheres. Each element is made from different spheres containing only 1 type of atom

Question 3

What did Thompson discover ?

Answer 3

ELECTRON .Plum pudding model suggested negative charges randomly distributed in a sea of positive charge

Question 4

What did Rutherford discover ?

Answer 4

PROTON+NUCLEUS. Alpha particle scattering experiment proved that atoms were mainly empty space as most particles passed through, nucleus was positively charges and mass is concentrated in nucleus as some particles were reflected back

Question 5

What did Bohr discover ?

Answer 5

Atomic model - electrons orbit nucleus at specific energy levels/shells

Question 6

What proof supported Bohr ?

Answer 6

When EM radiation is absorbed electrons move between shells and move down when radiation is emitted

Question 7

Why did Bohr want to disprove Rutherford’s theory ?

Answer 7

Didn’t believe clouds of electrons could collapse into positive nuclei

Question 8

What did Chadwick discover ?

Answer 8

NEUTRON

Question 9

What is the current understanding of the atom which disproves previous theories ?

Answer 9

Electrons don’t have the same energy in shells , instead there are sub shells which explain ionization trends

Question 10

Explain the chemical and physical properties of isotopes

Answer 10

• Chemical properties are identical as same electronic configuration
• Physical properties ( density ) can differ

Question 11

What is Mr used for ?

Answer 11

Covalent compounds / simple molecules

Question 12

What is relative formula mass used for ?

Answer 12

Ionic compounds / giant structures

Question 13

Define relative atomic mass (Ar)

Answer 13

The weighted mean mass of an atom of an element compared with one twelfth of a mass of an atom of carbon-12

Question 14

Define ion

Answer 14

An atom or molecule that is charged due to the loss or gain of one or more electrons

Question 15

Define isotope

Answer 15

Atoms of the same element with the same number of protons but a different number of neutrons + different masses

Question 16

Define relative isotopic mass

Answer 16

The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12

Question 17

State 2 differences between isotopes of the same element

Answer 17

• Different number of neutrons
• Different mass numbers

Question 18

State similarities and differences of isotopes of the same element

Answer 18

• Same number of protons AND electrons
• Different number of neutrons

Question 19

How do you calculate the number of copper atoms in a sample from mass, percentage by mass and relative atomic mass ?

Answer 19

mass x % by mass
————————— x avagadros
Relative atomic mass

Question 20

What isotope is used as the standard against which the masses of 2 isotopes are measured ?

Answer 20

Carbon-12

Question 21

State what is meant by the term atomic number

Answer 21

The number of protons IN THE NUCLEUS