Atomic structure, periodic table and calculation paper 2

Question 1

What is an atom

Answer 1

an atom is the smallest part of an element

Question 2

What is a molecule

Answer 2

A molecule is made of a fixed number of atoms covalently bonded together.

Question 3

Proton neutron and electron mass

Answer 3

Proton - 1
Neutron - 1
Electron - almost negligible

Question 4

Proton neutron electron charge

Answer 4

Proton - 1
Neutron - 0
Electron - -1

Question 5

What is atomic mass

Answer 5

The number of protons in an atom.

Question 6

What is mass number

Answer 6

The number of protons and neutrons in an atom.

Question 7

What is relative atomic mass

Answer 7

The average mass of an atom compared to 1/12th the mass of carbon-12

Question 8

What are isotopes

Answer 8

Atoms of the same element (same number of protons) but with a different number of neutrons.

Question 9

Groups are

Answer 9

Columns, they show the number of atoms in the outer shell

Question 10

Periods are

Answer 10

Rows, they show the number of shells in an atom

Question 11

Metals have oxides which are

Answer 11

basic, reacting with acids to give a salt and water

Question 12

Non metals have oxides which are

Answer 12

acidic or neutral

Question 13

why the noble gases (Group 0) do not readily react

Answer 13

The noble gases are inert (unreactive) because they have a full outer shell of electrons.

Question 14

What is mole

Answer 14

unit for the amount of a substance

The mass of 1 mole of a substance is the relative formula mass (Mr) of the substance in grams

Question 15

mol =

Answer 15

mass / Mr

grams over rams

Question 16

What is the theoretical percentage yield

Answer 16

The theoretical yield is the amount of product that you would expect to get.

Question 17

percentage yield =

Answer 17

actual amount of a product / theoretical percentage yield

Question 18

Finding the formula of a metal oxide experimentally

Answer 18

Finding the formula of a metal oxide experimentally
- Weigh a crucible and lid
• Place the magnesium ribbon in the crucible, replace the lid, and reweigh
• Calculate the mass of magnesium
• Heat the crucible with lid on until the magnesium burns
• Lift the lid from time to time (this allows air to enter)
• Stop heating when there is no sign of further reaction
• reweigh
• Repeat the heating , cooling and reweigh until two consecutive masses are the same
• Calculate the mass of magnesium oxide formed

Question 19

Finding the formula of a salt containing water of crystallisation

Answer 19

When some substances crystallise from solution, water becomes chemically bound up with the salt. This is called water of crystallisation and the salt is said to be hydrated.
The difference of mass before and after heating is the mass of the water lost

Question 20

What is the empirical formula

Answer 20

the simplest whole-number ratio between atoms/ions in a compound

Question 21

What is a molecular formula

Answer 21

the actual number of atoms of each type of element in a molecule.

Question 22

concentration ( mol/dm3) =

mol =

Answer 22

mol / volume

concentration x volume

Question 23

volume of a gas =

Answer 23

mol x 24 dm3

Question 24

To determine the formula of a metal oxide by combustion

Answer 24

Weigh a crucible and lid
Place the magnesium ribbon in the crucible and reweigh
Calculate the mass of magnesium
Heat the crucible with lid on until the magnesium burns
Lift the lid from time to time
Stop heating when there is no sign of further reaction
Allow to cool and reweigh
Repeat until two consecutive masses are the same
Calculate the mass of magnesium oxide formed- empirical formula