Why do the elements in the same group react in similar ways?

Because their atoms have the same number of electrons in the outer shell, and it is the outer electrons that take part in reactions.

Why are the Group 0 elements almost completely unreactive?

Because their atoms already have a full outer shell, so there is no tendency to lose, gain or share electrons.

An atom has the electron arrangement 2,8,7. Predict how it will react and what ion it will form.

It will gain one electron to complete its outer shell, forming an ion with a single negative charge.

OCR GCSE Chemistry A J248

Chemical Reactions

Topic overview Writing formulae of elements and compounds Balanced equations, and deducing formulae from ions Ionic equations, and state symbols The mole and the Avogadro constant Conservation of mass, and changes of mass in open systems Stoichiometry, and calculating reacting masses Exothermic and endothermic reactions, and reaction profiles Activation energy, and bond energy calculations Oxidation and reduction, by oxygen and by electrons Acids, alkalis and neutralisation The ionic equation for neutralisation, and reactions of acids Dilute and concentrated, weak and strong The pH scale, and hydrogen ion concentration pH as a factor of ten, and measuring pH Products at the electrodes, and molten ionic compounds Electrolysis of aqueous solutions Inert and non-inert electrodes

Elements, Compounds and Mixtures

Topic overview Purity, and melting point data Relative formula mass and empirical formulae Formulations, and separating mixtures Paper and thin layer chromatography Interpreting chromatograms and Rf values Choosing a purification method Metals and non-metals in the Periodic Table Electron arrangement and position in the Periodic Table Ionic, covalent and metallic bonding compared Dot and cross diagrams, and the limits of models Reactions, electron arrangement and Mendeleev's table Carbon's four bonds, and the variety of organic compounds Diamond, graphite, fullerenes and graphene Bond strength, intermolecular forces and predicting state Bulk properties of ionic, molecular and giant structures Nanoparticles: size and surface area to volume Uses and risks of nanoparticulate materials

Global Challenges

Topic overview Extracting metals by reduction and by electrolysis Biological methods of metal extraction Rate against yield in industry, and reaction conditions The Haber process and fertiliser production Nitrogen, phosphorus and potassium in agriculture Life cycle assessment Recycling, and the decisions behind it Alloys, and the corrosion of metals Comparing glass, ceramics, polymers, composites and metals Functional groups and homologous series Predicting the products of organic reactions Addition polymerisation Condensation polymerisation, and making a polymer DNA and other natural polymers Fractional distillation of crude oil The fractions, and crude oil as a feedstock Dependence on hydrocarbons, and cracking Chemical cells and fuel cells The Earth's early atmosphere, and how oxygen developed The greenhouse effect, and evidence for climate change Effects of carbon dioxide and methane, and air pollutants Producing potable water

Monitoring and Controlling Chemical Reactions

Topic overview Concentration in mol/dm³, and titration Titration calculations, and the mass of a solute Molar gas volume and the volumes of gases Theoretical mass and percentage yield Atom economy, and choosing a reaction pathway Measuring the rate of a reaction, and rate graphs Factors affecting rate, and collision theory Surface area and rate Catalysts and how they work Reversible reactions and dynamic equilibrium Changing the conditions of an equilibrium Activation energy, and enzymes as catalysts

Particles

Topic overview The particle model and changes of state Limitations of the particle model How the atomic model changed, and the structure of the atom The size of atoms, and the subatomic particles Calculating protons, neutrons and electrons

Predicting and Identifying Reactions

Topic overview Groups 1, 7 and 0, and why they behave as they do Transition metals Predicting reactivity from the Periodic Table Reactivity of metals with water and acids Tests for oxygen, hydrogen, carbon dioxide and chlorine Tests for aqueous cations and anions Flame tests, and identifying metal ions Identifying a species from test results Instrumental methods of analysis

Elements, Compounds and Mixtures

Reactions, electron arrangement and Mendeleev's table

3 things to know
Paper 3

Overview

Why a group reacts alike, the reactivity trends in Groups 1, 7 and 0, predicting how an atom with 2,8,7 reacts, how Mendeleev ordered the elements and left gaps, and ordering by atomic number.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why are the Group 1 elements so reactive?

Key term

Why does reactivity increase going down Group 1?

Key term

Why does reactivity decrease going down Group 7?

Questions from this subtopic

Each one with the model answer underneath.

1
Why do the elements in the same group react in similar ways?
Model answer
Because their atoms have the same number of electrons in the outer shell, and it is the outer electrons that take part in reactions.
2
Why are the Group 1 elements so reactive?
Model answer
Because each atom has just one outer electron, which is easily lost to form a positive ion.
3
Why does reactivity increase going down Group 1?
Model answer
Because the outer electron is further from the nucleus and better shielded by inner shells, so it is lost more easily.
4
Why does reactivity decrease going down Group 7?
Model answer
Because the outer shell is further from the nucleus and better shielded, so an extra electron is attracted less strongly.
5
Why are the Group 0 elements almost completely unreactive?
Model answer
Because their atoms already have a full outer shell, so there is no tendency to lose, gain or share electrons.
6
An atom has the electron arrangement 2,8,7. Predict how it will react and what ion it will form.
Model answer
It will gain one electron to complete its outer shell, forming an ion with a single negative charge.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Chemical Reactions

Elements, Compounds and Mixtures

Global Challenges

Monitoring and Controlling Chemical Reactions

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Values 7.

belowaboveat

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe products sit at a higher energy level than the reactants.

BThe activation energy, the energy that must be supplied before the reaction can happen.

CThe reactants, the products, the activation energy and the overall energy change.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Sodium ions give a bright yellow flame colour.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Elements, Compounds and Mixtures, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.