PERIODIC TABLE

How are elements arranged in the periodic table.

Elements are arranged in order of increasing atomic number.

In terms of subshells, how is periodic table divided up?

Divided into s,p,d and f blocks

The blocks denotes the subshells the elements; valence electrons are in.

What does the group and period of an element show.

Period - tells you how many electron shells the atom has.

Group - tells you how many electrons are in the atom's outer shells.

Define oxidation in terms of electron transfer.

Oxidation is the loss of electrons

Define reduction in terms of electron transfer

Reduction is the gain of electrons

What is the general trend in first ionisation energy across Period 2 and Period 3.

As you go along the period, first ionisation energy increases.

Explain the reason for the drop in ionisation energy between nitrogen and oxygen in period 2.

The electron being removed from oxygen is in an electron pair so the electron is removed more easily due to repulsion between the two electrons.

Explain the drop in ionisation energy between magnesium and aluminium in Period 3:

The __________ being removed from aluminium is in the ___ orbital, not the ___ orbital.

The 3p orbital is at a slightly _______ energy level.

The electron is found _________ from the nucleus in the 3p orbital

Aluminium has a _______ ionisation energy.

The electron is ____ attracted to the nucleus due to the increased distance and _________ from the 3s orbital.

electron 3p 3s

higher

further

lower

less

shielding.

Why does first ionisation energy increase across a period.

• The number of protons is increasing whilst the atomic radius is decreasing.

• Higher nuclear charge attracting the outer electrons.

• There is not much change in shielding across the period so this does not have a significant effect.

Explain the trend in IE down a group in the periodic table.

• Decreases

• Amount of shielding increases along with atomic radius.

• Outer electron is attracted more weakly to the nucleus, making it easier to remobe.

What is the trend of electronegativity across a period.

• Electronegativity increases

• More protons and decreasing atomic radius

• increasing nuclear attraction to electron density.

Trend of electronegativity down a group.

• Electronegativity decreases

• Electron shielding and atomic radius increases

• Nuclear attraction to the bonding pair weakens.

How do group 2 elements react with oxygen?

2X + O2 ⟶ 2XO Where X is the Group 2 element.

How do Group 2 elements react with water.

X + 2H2O ⟶ X(OH)2 + H2 Where X is the Group 2 element.

What is the chemical equation for the reaction between calcium and water?

Ca + 2H20 --> Ca(OH)2 + H2

What is the chemical equation for the reaction between strontium and oxygen

2Sr + O2 --> 2SrO

What is the chemical equation for the reaction between magnesium chloride and sodium carbonate.

MgCl2 + NacCO3 --> MgCO3 + 2NaCl

What is the chemical formula of the compound formed when Barium ions react with sulfate ions.

Barium ions --> Ba2+

Sulfate ions --> SO42-

Barium Sulfate: BaSO4

Describe how you would carry out a flame test.

• Clean a nichrome wire using HCl

• Turn the Bunsen burner onto the blue flame.

• Dip the wire in a solution of the substance being tested.

• Place the wire in the flame and record the flame colour.

What colour is observed in the flame test for lithium ions.

Crimson flame.

What colour is observed in the flame test for sodium ions.

Yellow Flame

What colour is observed in the flame test before potassium ions.

Lilac Flame

What colour is observed in the flame test for calcium ions.

Orange-red flame.

What colour is observed in the flame for strontium ions.

Red flame.

Why must the wire be cleaned before carrying out a flame test.

To remove any unwanted ions that might obscure the colour of the flame.

Why can a flame test not be used when a compound contains a mixture of metal ions.

The flame colour of the ions will blend together so the individual flames colours won't be seen and the ions can't be identified.

Explain the trend in reactivity down in Group 1 from lithium to potassium.

In order to react, group 1 elements lose an electron to form a 1+ ion.

Down group 1, the atomic radius and shielding increases so the outer electron is lost more easily.

Reactivity increases down Group 1.

Explain the trend in reactivity down Group 2 from Magnesium to Barium

In order to react, Group 2 elements lose two electrons to form 2+ ions.

Down group 2, the atomic radius and shielding increases so the outer electrons are lost more easily.

Reactivity increases down Group 2.

What is the trend of thermal stabilities of Group 1 and 2 carbonates.

The thermal stabilities of Group 1 and 2 carbonates increase down the group.

What is the trend in thermal stabilities of Group 1 and 2 nitrates

The thermal stabilities of Group 1 and 2 nitrates increase down the group

What is the trend in solubility of Group 2 hydroxides down the group.

The solubility of Group 2 hydroxides increases down the group

What is the trend of Group 2 sulphates down the group

The solubility of Group 2 sulfates decreases down the group

What is produced when a Group 1 and Group 2 hydroxide react with a dilute acid.

Salt and Water

What is the chemical equation for the reaction between NaOH and HCl

NaOH+ HCl --> NaCl + H2O

What is produced when a group 1 or group 2 oxide reacts with a dilute acid.

Salt and Water

What is the chemical equation for the reaction between lithium oxide and dilute sulfuric acid.

Li2O + H2SO4 --> LiSO4 + H2O

What are the group 7 elements often referred to as?

The halogens

Why do the halogens exist in different states at room temperature.

At room temp, chlorine is a gas, bromine is a liquid. and iodine is a solid because they have different melting points. As you go down the group, melting and boiling point increases.

Why does melting and boiling point increase down Group 7

The molecules get bigger and the number of electron shells increases down the group. This means there are more intermolecular forces to overcome during melting/boiling, so more energy is required to change state

What is produced when a metal reacts with a halogen?

A salt

Why does reactivity decrease down Group 7

The outer shell is further from the nucleus, and electron shielding increases.

Attraction between the nucleus and outer electrons decreases, so it is harder for the atom to gain an electron, meaning reactivity decreases

Link the reactivity trend of the halogens to the relative oxidising power of the halogens

Reactivity decreases down Group 7

This means the oxidising power of the halogens also decreases down the group because it's harder for the atom to gain an electron

How can halide ions be identified in a solution?

Add Nitric acid followed by silver nitrate solution. Silver halide precipitates will form. Ammonia solution can be added to further distinguish between the halide precipitates.

Silver chloride: White ppt soluble in dilute ammonia

Silver bromide: Cream ppt soluble in concentration ammonia

Silver Iodide: Yellow precipitate insoluble in ammonia

What is a redox reaction?

A redox reaction is one in which oxidation and reduction occur on different species simultaneously

When does a halogen displacement reaction occur?

When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.

Why can't iodine not displace chloride or bromide ions from an aqueous ionic solution?

Displacement will only occur if iodine is more reactive than the halogen in the ionic compound.

• Reactivity decreases down the group and iodine is below chlorine and bromine so no displacement reactions will take place.

What is the chemical equation for the reaction between bromine and potassium iodide?

Br₂ + 2KI --> I₂ + 2KBr

What type of reactions are halogen and halide ions displacement reactions?

Redox

What is a common use of chloride and fluoride ions?

The ions are used in water treatment because they kill bacteria in water.

What are the health and ethical debates surrounding the use of chloride and fluoride ions in water?

Chlorine is toxic it shouldn't be put into water supplies.

• People should have the choice about whether their water is treated with these ions.

What is a precipitation reaction?

A reaction in which two soluble salts combine to form an insoluble salt.