What do elements in the same group have in common about their outer-shell electrons?
They have the same number of outer-shell electrons.
AQA GCSE Combined Science: Trilogy (8464) — Chemistry — Foundation · 5.11
Revise AQA GCSE Combined Science: Trilogy (8464) — Chemistry — Foundation specification point 5.11, Key ideas, with free active-recall flashcards. Flip through the set or review every question and answer below.
1 / 36
What do elements in the same group have in common about their outer-shell electrons?
They have the same number of outer-shell electrons.
Why do elements in the same group tend to have similar chemical properties?
They have the same number of outer-shell electrons, which determine how atoms take part in chemical reactions.
What are all substances made from?
Atoms.
About how many different elements are there?
About 100.
What are the basic building blocks from which other substances are made?
Elements.
What is an atom?
The smallest part of an element that can exist as that element.
What is an element?
A pure substance made from only one type of atom.
What does periodicity mean for elemental properties?
Patterns in chemical and physical properties recur as atomic number increases, though values do not repeat identically.
What helps explain recurring chemical behaviour across the periodic table?
Repeated patterns in outer-shell electron arrangements.
How does atomic structure influence physical properties?
It influences the bonding and structures that contribute to physical properties.
What happens to electrons between atoms during ionic bonding?
Electrons are transferred from atoms of one element to atoms of another.
How does an atom’s charge change when it loses or gains electrons?
Losing electrons forms a positive ion; gaining electrons forms a negative ion.
What is an ionic bond?
The strong electrostatic attraction between oppositely charged ions.
What is a covalent bond?
A bond formed when atoms share a pair of electrons.
Why does a shared pair of electrons hold covalently bonded atoms together?
The shared electrons are attracted to the nuclei of both atoms.
How can covalent bonds change during chemical reactions?
They can form or be rearranged.
What is a molecule?
A group of bonded atoms with a particular three-dimensional arrangement.
How does molecular shape influence chemical and physical behaviour?
It affects how the molecule interacts with other particles.
What two features of a molecule influence its behaviour?
Which atoms are present and how they are arranged.
What is a giant structure?
An extended arrangement of very large numbers of joined particles, rather than separate small molecules.
Which two structural factors influence properties such as strength, melting point and electrical conductivity?
The arrangement of particles and the nature of the bonding.
How much energy is needed to overcome strong bonding throughout a giant structure?
A substantial amount of energy.
What must be present for a structure to conduct electricity?
Charged particles that can move.
What is activation energy?
The minimum energy needed to overcome the energy barrier for a reaction.
What energy condition must a collision meet for it to lead to a reaction?
The colliding particles must have sufficient energy to overcome the reaction’s energy barrier.
At the same temperature, how does a higher activation energy generally affect the reaction rate?
It reduces the proportion of collisions with enough energy to react, contributing to a slower reaction rate.
What happens in a proton-transfer reaction?
A hydrogen ion, , moves from one species to another.
What are the respective roles of an acid and a base in proton transfer?
The acid donates a proton; the base accepts it.
What is oxidation in terms of electron transfer?
The loss of electrons by a species.
What is reduction in terms of electron transfer?
The gain of electrons by a species.
Why do oxidation and reduction occur together in an electron-transfer reaction?
Electrons lost by one species are gained by another.
What is a redox reaction?
A reaction in which oxidation and reduction occur together.
What does conservation of energy mean for a reacting system and its surroundings?
Their total energy remains constant: energy can be transferred or change form, but is neither created nor destroyed.
How do bond breaking and bond forming differ in their energy changes?
Breaking bonds requires energy; forming bonds releases energy.
What determines whether a reaction transfers energy overall to or from its surroundings?
The balance between energy required to break bonds and energy released when bonds form.
How does the direction of overall energy transfer differ between exothermic and endothermic reactions?
An exothermic reaction transfers energy to the surroundings; an endothermic reaction transfers energy from the surroundings.