Topic 1-Atomic Structure and Periodic Table

Question 1

What is an atom?

Answer 1

An atom is the smallest part of an element that can exist

Question 2

What is an element?

Answer 2

An element is a substance made up of one type of atom only

Question 3

What is a compound?

Answer 3

A compound is 2 or more elements chemically joined together in fixed proportions. They are held together by chemical bonds

Question 4

What is a mixture?

Answer 4

A mixture is 2 or more elements or compounds NOT chemically joined together

Question 5

What is the mass and charge of:
A proton
A neutron
An electron

Answer 5

Mass Charge
Proton 1 +1
Neutron 1 0 (neutral)
Electron 0 -1

Question 6

Label this atom symbol:

23
Na
11

Answer 6

Mass number—> 23
(Tot. No. of protons       Na
and neutrons)                                 
Atomic number—>11
(Number or protons+electrons)

Question 7

What is an isotope?

Answer 7

Isotopes are different forms of the same element. They have the same number of protons but different number of neutrons.
For example: Carbon 12 and Carbon 13

Question 8

What is the history of the model of the atom?

Answer 8

John described atoms as solid spheres. However Thomson from his experiments concluded that atoms consisted of a random assortment of negative and positive charges with electrons inside, also known as the plum pudding model.
After, Rutherford carried out the alpha particle scattering experiment and proved the plum pudding model to be wrong. He fired alpha particles to a sheet of gold and from the PP model, they expected the particles to go through and deflect at most. However even though some did pass through the sheet, some deflected more than expected. This concluded that the atom is an empty space, that the mass of the atom was mostly consisted in the centre of a tiny nucleus and that it consisted of positive charge.
After this, Niels Bohr said that electrons orbiting the nucleus did so at certain distances and energy levels. His theory was supported by other experiments.
Later on, the existence of protons was proved and Chadwick proved the existence of neutrons.

Question 9

In what ways can we separate mixtures?

Answer 9

Chromatography, Filtration, Evaporation,

Crystallisation, Distillation and Fractional Distillation

Question 10

How has the periodic table been developed?

Answer 10

First, John Newlands ordered his table in order of atomic masses. He realised that similar properties occurred at every eighth element (the law of octaves). He saw a periodic pattern. However, elements were placed in the wrong group because he didn’t take into account their properties

Dmitri Mendeleev took into account some properties and also atomic masses but not strictly. He left gaps in as he believed there were undiscovered elements. Isotopes proved that Dmitri was right in not ordering them strictly by their atomic masses but also their properties.

Question 11

What does the modern periodic table consist of?

Answer 11

The periodic table helps you see patterns in properties. They are laid out in order of increasing number of atomic/proton number. This means that there are increasing patterns in properties. Metals are on the left and non metals on the right.

Similar properties form columns called groups. The group number tells you how many electrons they have on their outer shell. Except for group 0/8 as helium has 2 electrons on its outer shell.

The rows are called periods and they tell you how many full electron shells there are

Question 12

Difference/Similarities between metals and non metals?

Answer 12

Metals form positive ions when the react. They are strong, malleable , can conduct electricity and heat and have metallic bonding. They also have high melting and boiling points

Nonmetals do not have metallic bonding, are brittle, cannot conduct electricity, have lower density, they are dull and aren’t always solid at room temp.

Question 13

What are the transition metals?

Answer 13

Transition metals are in the middle of the periodic table. They are good conductors of heat and electricity, they are very dense, strong and shiny. they make good catalysts, less reactive and can have more than one ion

Question 14

Describe Group 1 Metals:

Answer 14

Group one metals are soft metals and are very reactive as you go down. This is because they all have one electron on their outer shell, so as the atom gets bigger and the atomic mass increases as you go down, the attraction between the nucleus and outer electron decreases so it gets lost easily causing a reaction. They have low melting and boiling points, and have a low density

Question 15

Group 1 metal reactions with water, chlorine and oxygen:

Answer 15

I

Question 16

Describe group 7:

Answer 16

As you go down, they become less reactive. This is because it is harder to gain and extra electron as the atomic mass increases, the atom gets bigger and the outer electron gets further away from the nucleus. This means the attraction is not strong therefore cannot gain and extra electron. Group 7 are called the halogens. These halogens can share electrons with another non metal (covalent bonding) to get a full outer shell. When they do this they form simple molecular structures.
Halogens form 1- ions when they react with metals, they form ionic structures. Since group 7 decrease in reactivity, displacement reactions can take place for example chlorine can displace bromine

Question 17

Describe Group 0

Answer 17

They all have 8 electrons on their outer shell except for helium which has 2. They are monatomic gases meaning they are single atoms not bonded to each other.
They are colourless gases at room temperature and are not flammable. Their boiling points increase as you go down, and increase in atomic mass (so they get heavier) this is due to increase in electrons so they have to over come greater intermolecular forces. There are more intermolecular forces in smaller molecules