Atomic Structure and The Periodic Table

Question 1

What is an atom and what is made from it?

Answer 1

Atoms are the smallest part of an element that can exist. EVERYTHING is made up of atoms.

Question 2

What is a compound?

Answer 2

A compound is a substance that is chemically combined in fixed proportions by two or more elements.

Question 3

What is an element?

Answer 3

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

Question 4

How are elements and compounds represented?

Answer 4

Using symbols e.g Iron -> Fe

Question 5

Form of word equations:

Answer 5

Reactants -> Products

Question 6

An example of a word equation:

Answer 6

Sodium + Chlorine -> Sodium Chloride

Question 7

Balancing equations:
Na + I2 -> NaI

Answer 7

2Na + I2 -> 2NaI

Question 8

Describe what a mixture is

Answer 8

A mixture contains two or more substances that are not chemically combined.

Question 9

Mixtures can be separated by physical processes such as:

Answer 9

Filtration, Distillation, Crystallisation and Chromatography

Question 10

How do you use filtration and what is it best used for?

Answer 10

1. One beaker contains a mixture of solid and liquid, the other contains a funnel with filter paper

The solid and liquid mixture is poured into the filter funnel.

2. The liquid drips through the filter paper into the beaker below, but the solid particles are caught in the filter paper.

Filtration is used for separating insoluble solids from liquids, e.g. sand and water.

Question 11

How does crystallisation work and what is it best used for?

Answer 11

1. A solution is placed in an evaporating basin and heated with a Bunsen burner.
2. The volume of the solution has decreased because some of the water has evaporated. Solid particles begin to form in the basin.
3. All the water has evaporated, leaving solid crystals behind.

The process of producing crystals from a solution by evaporating the solvent.

Question 12

How does simple distillation work and what is it best used for?

Answer 12

1. Salty water is heated.
2. The water vapour cools in the condenser and drips into a beaker.
3. The water has condensed and is now in the beaker, the salt stays behind

Separation method used to separate a solvent from a solution.

Question 13

How is fractional distillation used and what is it best used for?

Answer 13

1. Water and ethanol solution is heated
2. The ethanol evaporates first, cools, then condenses
3. The water left evaporates, cools, then condenses

Fractional distillation
is used to separate different liquids from a mixture of liquids.

Question 14

How is paper chromatography used and what is it best used for?

Answer 14

1. Ink or plant dye is dotted along the pencil line.
2. As the paper is lowered into the solvent, some of the dye spreads up the paper
3. The paper has absorbed the solvent, and the dye has spread further up the paper

Paper
chromatography
is used to separate mixtures of
soluble
substances.

Question 15

Describe Dalton’ Model

Answer 15

Dalton thought the atom was a solid sphere therefore it didn’t contain electrons, protons and neutrons as they were yet to be discovered.

Question 16

Describe The Plum Pudding Model by J.J Thomson:

Answer 16

The discovery of electrons led to the plum pudding model which is a cloud of positive charge with negative electrons embedded in it. Protons and neutrons were yet to be discovered.

Question 17

Describe the Alpha Scattering Experiment by Ernest Rutherford:

Answer 17

Rutherford fired small, positively charged particles (alpha particles) at a piece of thin gold foil. Some particles travelled straight through which informs us that the atom is mainly composed of empty space. Although some particles bounced back and many were deflected due to the positively charged nucleus which they then discovered.

Question 18

Describe the Nuclear Model by Rutherford:

Answer 18

The nuclear model then replaced the plum pudding model to suggest that the electrons orbit the nucleus.

Question 19

The discovery of the neutron and who is was by?

Answer 19

James Chadwick discovered the neutron in 1932. He concluded that the protons and the neutrons are in the nucleus whilst the electrons orbit the nucleus in shells.

Question 20

Relative charge:
Electrons -
Protons -
Neutrons -

Answer 20

-1
1
0

Question 21

Relative mass:
Electrons -
Protons -
Neutrons -

Answer 21

1/2000 - very small
1
1

Question 22

Where is most of the mass concentrated in the atom?

Answer 22

In the nucleus

Question 23

Isotopes

Answer 23

forms of an element that have the same number of protons but different numbers of neutrons.

Question 24

Abundance of an isotope

Answer 24

The more abundant an isotope, the closer the atomic mass will be to the atomic mass of that isotope.

Question 25

Relative atomic mass

Answer 25

a weighted average of the masses of the atoms of the isotopes.

Question 26

Calculate the relative atomic mass of Cu63 with an abundance of 4 and Cu62 with an abundance of 2.

Answer 26

(63x4)+(62x2)/100= 2.5 percent

Question 27

Describe how electrons fill energy levels in atom.

Answer 27

The electrons in an atom occupy the lowest available energy level first. This is the shell nearest the nucleus. When this shell is full the electrons begin to occupy the next energy level.

Question 28

How is the Periodic Table arranged?

Answer 28

increasing in atomic number

Question 29

Describe how elements with similar properties are placed in the periodic table

Answer 29

Elements in the same group have similar chemical properties. This is because they have the same number of outer electrons and the same valency.

Question 30

Explain why elements in the same group have similar properties

Answer 30

This is because they have the same number of outer electrons and the same valency.

Question 31

Describe the early attempts to classify elements

Answer 31

Before discovering protons, neutrons and electrons, scientists tried to classify the elements by arranging them in order of their atomic mass

Question 32

Explain the creation and attributes of Mendeleev's periodic table

Answer 32

He took into account the properties of the elements and their compounds. This meant that his table: had gaps in it showed elements with similar chemical properties lined up in groups However, from their atomic weights, some pairs of elements next to each other were in the wrong order.

Question 33

Physical properties of metals

Answer 33

high melting points good conductors of heat and electricity high density ductile malleable

Question 34

Physical properties of non-metals

Answer 34

low melting points poor conductors of heat and electricity low density

Question 35

Explain how the atomic structure of metals and non-metals relates to their position in the periodic table

Answer 35

The proton number determines the element itself and its position.

Question 36

Describe noble gases (group 0) and explain their lack of reactivity

Answer 36

The atoms of noble gases already have complete outer shells, so they have no tendency to lose, gain, or share electrons. This is why the noble gases are inert and do not take part in chemical reactions.

Question 37

Describe the properties of noble gases and the trend in the Periodic Table

Answer 37

odourless, colourless, monotonic gases that have low chemical reactivity, low melting + boiling points and as you move down the group of noble gases their atoms increase as well as their melting and boiling points

Question 38

Describe the reactivity and properties of group 1 alkali metals with reference to their electron arrangement and predict their reactions

Answer 38

The reactivity of Group 1 elements increases as you go down the group because: the atoms get larger. the outer electron gets further from the nucleus. the attraction between the nucleus and outer electron gets weaker – so the electron is more easily lost. soft, reactive metals with low melting points

Question 39

Lithium's reaction with water

Answer 39

Lithium + water -> Lithium hydroxide + hydrogen effervescence and floats

Question 40

Sodium's reaction with water

Answer 40

moves on the surface and effervescence

Question 41

Potassium's reaction with water

Answer 41

moves vigorously on the surface of the water and ignites which results in a lilac flame (sometimes an explosion)

Question 42

Test for hydrogen

Answer 42

lit splint is placed inside a tube and makes a squeaky pop

Question 43

Test for oxygen

Answer 43

a glowing lit splint relights

Question 44

Test for carbon dioxide

Answer 44

lime water turns cloudy

Question 45

Test for chlorine

Answer 45

damp litmus paper bleaches white

Question 46

Describe the reactions of group 7 halogens with metals and non-metals

Answer 46

The group 7 elements are all reactive non-metals. They react with metals to form metal halides, and with hydrogen to form acidic hydrogen halides. Reactivity decreases down the group.

Question 47

Describe the properties of transition metals and compare them with group 1 elements, including melting points and densities, strength and hardness, and reactivity (for CR, Mn Fe, Co, Ni & Cu)

Answer 47

Transition metals are much stronger, denser and harder than the group 1 elements. Their melting and boiling points are also much higher.

Question 48

Describe the properties of group 7 halogens and how their properties relate to their electron arrangement, including trends in molecular mass, melting and boiling points and reactivity

Answer 48

The melting points and boiling points of the halogens increase going down group 7, and their colour gets darker. They want to gain an electron to become stable.

Question 49

Properties of transition metals:

Answer 49

hard/ strong high melting points high density not very reactive can form ions