Topic 1 - Key Concepts in Chemistry

Question 1

Define compound

Answer 1

Two or more elements chemically bonded

Question 2

Define element

Answer 2

Substance made up of only one type of atom

Question 3

Mass of a proton

Answer 3

1 AMU

Question 4

Mass of a neutron

Answer 4

1 AMU

Question 5

Mass of an electron

Answer 5

Almost 0, 1/2000 AMU

Question 6

Define mass number

Answer 6

Number of protons + neutrons

Question 7

Define atomic number

Answer 7

Number of protons (in the nucleus)

Question 8

Charge of a proton

Answer 8

+1

Question 9

Charge of a neutron

Answer 9

0

Question 10

Charge of an electron

Answer 10

-1

Question 11

Define a molecule

Answer 11

Two or more atoms bonded together

Question 12

John Newlands and Mendeleev arranged their periodic table in order of…

Answer 12

atomic mass

Question 13

The modern periodic table is arranged in order of…

Answer 13

atomic number (proton number)

Question 14

Explain why Mendeleev left gaps in his periodic table

Answer 14

to make the pattern fit for undiscovered elements

Question 15

Explain why potassium and sodium are in the same group of the periodic table

Answer 15

They both have one electron in their outer shellThey react similarly

Question 16

Explain why chlorine and bromine are group 7 of the periodic table

Answer 16

Both have 7 electrons in their outer shell

Question 17

Explain why chlorine’s relative atomic mass is 35.5

Answer 17

Relative atomic mass is an average mass

Chlorine exists as Cl- 35 and Cl-37

75% is Cl-35 and 25% is Cl-37

(35 x 75 ÷ 100) + (37 x 25 ÷ 100) = 35.5

Question 18

Explain why Mendeleev swapped Tellurium and Iodine’s position in his periodic table.

Answer 18

• Iodine has similar properties to other group 7 elements
• Iodine had similar chemical reactions to other group 7 elements
• Iodine is also diatomic

Question 19

What subatomic particle did James Chadwick discover?

Answer 19

Neutron

Question 20

How did Mendeleev’s periodic table become accepted by scientists?

Answer 20

They discovered the elements he’d left gaps forand they had similar properties to those he’d precited

Question 21

Name two differences between Dalton and Rutherford’s model of the atom

Answer 21

Dalton said the atom was solid whereas Rutherford believed the atom was made of mostly empty space

Dalton believed that atoms were indestructible whereas the modern model of the atom is made of protons, neutrons and electrons

Question 22

Name particle A

Answer 22

Electron

Question 23

Which particle would be the electron. Explain your answer.

Answer 23

A

as it has the smallest mass so is deflected the most

or

it has is negative and attracted to the positive plate

Question 24

Name particle B

Answer 24

Neutron/Proton

Question 25

Name particle C

Answer 25

Neutron/Proton

Question 26

Which particle would be the proton. Explain your answer.

Answer 26

C

as it has the largest mass so is deflected the least

or

it has is positive and attracted to the negative plate

Question 27

Which particle would be the neutron. Explain your answer.

Answer 27

B

It has no charge so isn’t deflected by the magnetic field

Question 28

Answer 28

i) 90
ii) 222

Question 29

What is an isotope?

Answer 29

Atoms of the same element with the same number of protons and different numbers of neutrons

Question 30

Which scientist discovered the neutron?

Answer 30

James Chadwick

Question 31

Lithium’s relative atomic mass is 6.94. Is the Lithium-6 or Lithium-7 isotope more abundant? Explain your answer.

Answer 31

Lithium-7 as 6.94 is closer to 7

Question 32

Compare the structures of lithium-6 and lithium-7 by referring to their subatomic particles

Answer 32

They both have the same number of protons (3)

They both have the same number of electrons (3)

They both have different numbers of neutrons (4)

or Lithium-7 has one more neutron

Question 33

Answer 33

Question 34

What group of the periodic table would this atom be found in?

Answer 34

1 (it has one electron in its outer shell)

Question 35

What period of the periodic table would this atom be found in?

Answer 35

3 (it has three energy levels)

Question 36

Explain, in terms of electrons, why magnesium and calcium are both in the same group of the periodic table.

Answer 36

They both have two electrons in their outer shell

Question 37

What does the group number tell you about an element’s electron configuration?

Answer 37

The number of electrons in its outer shell

Question 38

What does the period number tell you about an element’s electron configuration?

Answer 38

The number of energy levels

Question 39

Draw the electron configuration of sodium

Answer 39

2,8,1

Question 40

What is the proton number (Z) of this atom?

Answer 40

11 (same as the number of electrons)