2.1.1 Atomic Structure and Isotopes and 2.1.2 Compounds, formulae and equations

Question 1

What was stated in Dalton’s atomic theory?

Answer 1

• Atoms are tiny particles made of elements
• Atoms cannot be divided
• All the atoms in an element are the same
• Atoms of one element are different to those of other elements

Question 2

What did Thompson discover about electrons?

Answer 2

• They have a negative charge
• They can be deflected by magnet and electric fields
• They have a very small mass

Question 3

Explain the plum pudding model

Answer 3

Atoms are made up of negative electrons moving around in a sea of positive charge

Question 4

What were Rutherford’s proposals after the gold leaf experiment?

Answer 4

• Most of the mass and positive charge of the atom are in the nucleus
• Electrons orbit the nucleus
• Most of atom’s volume is the space between the nucleus and the electrons
• Overall positive and negative charges must balance

Question 5

Explain the current model of the atom

Answer 5

• Protons and neutrons are found in the nucleus
• Electrons orbit in shells
• Nucleus is tiny compared to the total volume of atom
• Most of atom’s mass is in the nucleus
  Most of the atom is empty space between the nucleus and the electrons.

Question 6

What is the charge of a proton?

Answer 6

1+

Question 7

What is the charge of an electron?

Answer 7

1-

Question 8

What particle has the same mass as a proton?

Answer 8

Neutron

Question 9

Which two particles make up most of an atom’s mass?

Answer 9

Protons and neutrons

Question 10

Which letter is used to represent the atomic number of an atom?

Answer 10

z

Question 11

What does the atomic number tell us about an element?

Answer 11

Atomic number = number of protons in an atom

Question 12

Which letter represents the mass number?

Answer 12

a

Question 13

How is mass number calculated?

Answer 13

Mass number = Number of protons + number of neutrons

Question 14

How to calculate the number of neutrons?

Answer 14

Number of neutrons = mass number - atomic number

Question 15

Define isotope

Answer 15

Atoms of the same element with a different number of neutrons

Question 16

Why do different isotopes of the same element react in the same way?

Answer 16

• Neutrons have no impact on the chemical reactivity

- Reactions involve electrons, isotopes have the same number of electrons in the same arrangement

Question 17

What are ions?

Answer 17

Charged particles that are formed when an atom loses or gains electrons

Question 18

What is the charge of the ion when electrons are gained?

Answer 18

negative

Question 19

What is the charge of the ion when electrons are loss?

Answer 19

positive

Question 20

What is the unit used to measure atomic masses called?

Answer 20

Unified atomic mass

Question 21

Define relative atomic mass

Answer 21

The weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon 12

Question 22

What are the units of relative atomic mass?

Answer 22

No units

Question 23

Define relative isotopic mass

Answer 23

The mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon 12

Question 24

The relative isotopic mass is the same as which number?

Answer 24

Mass number

Question 25

Which two assumptions are made when calculating mass number?

Answer 25

1. Contribution of the electron is neglected

2. Mass of both proton and neutron is taken as 1.0 u

Question 26

How to calculate the relative molecular mass and the relative formula mass?

Answer 26

Both can be calculated by adding the relative atomic masses of each of the atom making up the molecule or the formula

Question 27

What are the uses of mass spectrometry?

Answer 27

• Identify unknown compounds
• Find the relative abundance of each isotope of an element
• Determine structual infomation

Question 28

How does a mass spectrometer work?

Answer 28

• The sample is made into positve ions
• They pass through the apparatus and are seperated according to mass to charge ratio
• A computer analyses the data and produces mass spectrum

Question 29

How is the group number related to the number of electrons?

Answer 29

Group number = number of electrons in the outer shell

Question 30

Does the group number indicate horizontal or vertical column in the periodic table?

Answer 30

Vertical column

Question 31

Do metals usually gain or lose electrons?

Answer 31

Lose electrons

Question 32

What are the 4 elements that don’t tend to form ions and why?

Answer 32

The elements are beryllium, boron, carbon and silicon

Requires a lot of energy to transfer outer shell electrons

Question 33

What are molecular ions?

Answer 33

Covalently bonded atoms that lose or gain electrons

Question 34

What is the charge of an ammonium ion?

Answer 34

+1

NH₄⁺

Question 35

What is the charge of a hydroxide ion?

Answer 35

-1

OH⁻

Question 36

What is the charge of a nitrate ion?

Answer 36

-1

NO₃⁻

Question 37

What is the charge of a carbonate ion?

Answer 37

-2

CO₃²⁻

Question 38

What is the charge of a sulfate ion?

Answer 38

-2

SO₄²⁻

Question 39

What is an empirical formula?

Answer 39

Simplest whole number ratio of atoms of each element present in a compound

Question 40

How to calculate empirical formula?

Answer 40

• Divide the amount of each element by its molar mass
• Divide the answers by the smallest value obtained
• If there is a decimal, divide it by a suitable number to make it into a whole number