Atoms, compounds, molecules and equations

Question 1

What do metal atoms usually do during reaction

Answer 1

When metal atoms react, they tend to lose their outer electrons to form positive ions

Question 2

How can you predict the charge of ions in group 1 and 2

Answer 2

If you look at the element in the periodic table. The group determines what charge it will be

Question 3

How can you predict the charges on the ions in group 3 metals (aluminum)

Answer 3

It is difficult to determine the charge of ions in group 3. However we know that. Aluminum forms a charge of 3+.

Question 4

Why are the charges of transition metals ions unusual

Answer 4

At the center of the periodic table, we have the transition metals. They are unusual as they can often form several positively charged ions

Question 5

Why are the charges of transition metals ions unusual

Answer 5

At the center of the periodic table, we have the transition metals. They are usual as they can often form several positively charged ions

Question 6

What ion does silver form

Answer 6

silver forms Ag+

Question 7

What ion does zinc form

Answer 7

Zn^2+

Question 8

What happens when a non-metal atoms form ions

Answer 8

When non-metal atoms form ions, they tend to gain electrons and form negative ions

Question 9

What happens to the name of the non-metal atom when it turns into an ion

Answer 9

The name of the ion turns to ide at the ends (suffix)

It only changes to ide if the non-metal has reacted with one other elements e.g (Lithium chloride)

Question 10

How can we use the periodic table to work out the charge on the non-metal ion produced

Answer 10

The group 5 elements nitrogen and phosphorus forms ions with a 3- charge

The group 6 elements oxygen and sulfur form ions with a 2- charge

The groups 7 elements form ions with a 1- charge

Question 11

What are the charges of the following non-metal ions :

Hydrogen, Ammonium, Hydroxide , Nitrate, Carbonate, Sulfate

Answer 11

H+

NH4+

OH-

NO3-

CO3 2-

SO4 2-

Question 12

What do all these ions apart from hydrogen have in common:

Hydrogen Ammonium, Hydroxide , Nitrate, Carbonate, Sulfate

Answer 12

All these ions apart from the hydrogen ion contain two different elements. These are called polyatomic ions

Question 13

Key facts to know about ionic compounds:

Answer 13

The charges of the individual ions must cancel out to produce an overall charge of zero

The charges of ions are never written down when we write the formula of an ionic compound

The little number to the right of brackets multiple everything within it

Question 14

How does zinc oxide get its charge

Answer 14

The 2+ charge on the zinc ion is canceled out by the 2- charge of the oxide ion.

Therefore, the compound has an overall charge of zero. Thus has a formula of ZnO

Question 15

What is the formula of:

ammonium nitrate

Lithium sulfide

Aluminum oxide

Answer 15

NH4NO3

Li2S

Al2O3

Question 16

Work out the formula of calcium nitrate

Answer 16

Ca = 2+

NO = 3-

Ca(NO3)2

Question 17

Explain what are isotopes

Answer 17

Isotopes are atoms of the same elements with different number of neutrons and different masses

Question 18

Key ideas of isotopes:

Answer 18

All isotopes of an element react in the same way as they all have the same electron configuration

The abundance of isotopes tell his how common each isotope is.

Question 19

Explain the function of the mass spectrometer

Answer 19

It determines the mass number and abundance of isotopes

Question 20

Explain how to interpret a mass spectrum

Answer 20

The peaks on the graph determine the number of isotopes

The y-axis shows the relative abundance of isotopes of the same elements which give the percentage of the total. (Often shown at the top of the peak)

On the x-axis there is an m/z ratio. This is the ratio of the mass of each ion and its charge. Almost all ions have a single positive charge. (Interpreted as the Relative mass of the ion)

Question 21

How are the extremely small masses of atom solved

Answer 21

This problem is solved through using relative mass

Question 22

Explain relative masses

Answer 22

Masses in Chemistry are relative to carbon-12 which is an isotope of carbon.

They are called relative masses as they are relative to carbon-12. The atoms of carbon-12 has a mass of 1. 1/12th of the mass of this atom is counted as 1

Question 23

Define relative isotopic masses

Answer 23

Relative isotopic mass is defined as the mass of an atom of an isotope compared with 1/12th the mass of carbon-12

Question 24

Key points of relative isotopic mass:

Answer 24

There is one relative isotopic mass for each isotope of an element

Relative isotopic mass is always a whole number. It is never a decimal

Relative isotopic mass has no units.

Question 25

Define relative atomic mass

Answer 25

Relative atomic mass is the weighted mean mass of an atom of an element compared with 1/12th the mass of carbon-12

Question 26

Key points of relative atomic mass :

Answer 26

The mean is weighted for the abundance of each isotope. How common an isotope is.

Relative atomic mass has no units

Virtually all of the relative atomic masses are not whole numbers. This is because it is a mean

Question 27

How to calculate relative atomic mass

Answer 27

(Relative isotopic mass of isotope 1 X percentage abundance of isotope 1 )

+

(Relative isotopic mass of isotope 2 X percentage abundance of isotope 2 )

Ar=———————————————————————————-

                                                  100

Question 28

What does the molecular formula show

Answer 28

It tells us the elements in a molecule and the number of atoms in each element

Question 29

Complications of molecular formula

Answer 29

It does not give us information about the structure of the molecule.

Question 30

Complications of molecular formula

Answer 30

It does not give us information about the structure of the molecule.

Question 31

What does the empirical formula show

Answer 31

It tells us the simplest whole-number ratio of the atoms of each element in a compound

Question 32

Why is the molecular formula not used for a giant ionic lattice

Answer 32

Ionic compounds form crystals consisting of a giant ionic lattice. These contain a vast number of ions.

It is not practical to write the formula showing the actual number of atoms in each element
(Number of atoms is extremely large / a larger crystal would contain more atoms than small crystals)

Question 33

How can the relative molecular mass be calculated

Answer 33

The relative atomic masses of a molecule is added together to calculate the relative molecular mass

Question 34

Define relative molecular mass

Answer 34

The relative molecular mass is defined as the weighted mean mass of a molecule compared with 1/12th the mass of an atom of carbon-12

It has the symbol of Mr

Question 35

Key ideas to calculate relative molecular mass

Answer 35

We do not use large number to calculate relative molecular mass. It only applies to one molecule.

Question 36

How to calculate the relative formula mass

Answer 36

It is calculated the same ways as relative molecular mass. However, the empirical formula of the chemical is used.

Question 37

When is relative atomic and molecular mass used

Answer 37

It is used for small covalent molecules

Question 38

When is empirical formula or relative formula mass used

Answer 38

When giant ionic structures are being used