2.1.1 and 2.1.2- atomic structure and isotopes, compounds, formula and equations.

Question 1

What was stated in Dalton’s atomic theory? (4 marks)

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 Thomson discover about electrons? (3 marks)

Answer 2

• They have a negative charge
• They can be deflected by magnet and electric field
• 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 was Rutherford’s proposal after the gold leaf experiment? (4 marks)

Answer 4

• Most of the mass and positive charge of the atom are in the nucleus
• Electrons orbit the nucleus
• Most of the 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 the 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

Which particle has the same mass as a proton?

Answer 8

Neutron

Question 9

Which two particles make a 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 about an element?

Answer 11

`Atomic number = The number of protons in an atom of that element

Question 12

Which letter represents the mass number?

Answer 12

A

Question 13

How is mass number calculated?

Answer 13

Number of protons + number of neutrons

Question 14

How to calculate the number of neutrons?

Answer 14

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? (2 marks)

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 an ion when electrons are gained?

Answer 18

Negative

Question 19

What is the unit used to measure atomic masses called?

Answer 19

Unified atomic mass unit, u

Question 20

Define relative atomic mass

Answer 20

The weighted mean mass of an atom of an element compared with one 12th of the mass of an atom of carbon-12.

Question 21

What is the unit of relative atomic mass?

Answer 21

No units

Question 22

Define relative isotopic mass

Answer 22

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

Question 23

The relative isotopic mass is the same as which number?

Answer 23

Mass number

Question 24

What two assumptions are made when calculating mass number?

Answer 24

• Contribution of the electron is ignored
• mass of proton and neutron is taken as 1.0 u

Question 25

How do you calculate the relative molecular mass and relative formula mass?

Answer 25

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

Question 26

What are the uses of mass spectrometry? (3 marks)

Answer 26

• To identify unknown compounds
• To find relative abundance of each isotope of an element
• `To determine structural information

Question 27

How does a mass spectrometer work?

Answer 27

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

Question 28

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

Answer 28

Group number indicates the number of electrons in the outer shell

Question 29

Is the group number the horizontal or vertical column in the periodic table?

Answer 29

Vertical column

Question 30

Do metals usually gain or lose electrons?

Answer 30

Lose electrons

Question 31

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

Answer 31

• The elements are beryllium, boron, carbon and silicon
• it requires a lot of energy to transfer outer shell electrons

Question 32

What are molecular ions?

Answer 32

Covalently bonded atoms that lose or gain electrons

Question 33

What is the empirical formula of a compound?

Answer 33

The simplest whole number ratio of atoms of each element present in a compound.