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The periodic table key terms
Use these key terms for The periodic table in AQA Chemistry 8462. The page is built from approved learning objectives for this topic and links back to the wider unit, topic hub, and related revision assets.
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key terms
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The periodic table
Key terms
atomic number
The number of protons in the nucleus of an atom, which determines the element's position in the periodic table.
periodic table
A tabular arrangement of elements organized by increasing atomic number, showing periodic trends in properties.
group
A column in the periodic table where elements share similar properties and have the same number of outer-shell electrons.
periodic table
A systematic arrangement of elements in order of atomic number, showing the relationships between them.
group
A column in the periodic table where elements have the same number of outer-shell electrons.
outer-shell electrons
Electrons located in the outermost shell of an atom that determine its chemical properties.
outer-shell electrons
Electrons located in the highest energy level of an atom that determine its chemical properties.
similar chemical properties
Chemical behaviors that are alike among elements in the same group due to their identical number of outer-shell electrons.
atomic number
The number of protons in the nucleus of an atom, which determines the element's position in the periodic table.
electron arrangement
The distribution of electrons in an atom's electron shells, which influences the element's chemical properties and position in the periodic table.
reactivity
the tendency of an element to undergo a chemical reaction, influenced by its position in the periodic table.
periodic table
a tabular arrangement of elements ordered by atomic number, showing periodic trends in properties.
atomic weight
The mass of an element's atoms, used by early scientists to arrange elements in the periodic table.
Mendeleev
A scientist who developed an early version of the periodic table and left gaps for undiscovered elements.
incomplete periodic tables
Early periodic tables lacked some elements and did not account for all properties.
arrangement by atomic weight
The method used by early scientists to organize elements before the discovery of subatomic particles.
inappropriate groups
Groups in the periodic table where elements do not share similar properties due to strict adherence to atomic weight order.
atomic weight order
The arrangement of elements based on their atomic weight, which led to misclassification in early periodic tables.
Mendeleev
A scientist who developed an early version of the periodic table and left gaps for undiscovered elements.
gaps
Spaces in the periodic table indicating the presence of undiscovered elements, as predicted by Mendeleev.
Mendeleev
A chemist who developed the periodic table and rearranged elements based on their chemical properties.
chemical properties
Characteristics of a substance that determine how it reacts with other substances.
Mendeleev
A chemist who developed the periodic table and rearranged elements based on their chemical properties.
predicted elements
Elements that were forecasted by Mendeleev based on gaps in his periodic table, which were later discovered.
isotope
Atoms of the same element with the same number of protons but different numbers of neutrons.
atomic weight order
The arrangement of elements based on their average atomic mass, which can be affected by the presence of isotopes.
testing predictions
The process of conducting experiments or observations to verify the accuracy of scientific hypotheses.
support or refute
To provide evidence that either confirms (supports) or disproves (refutes) a scientific idea.
metal
An element that reacts to form positive ions.
positive ion
A charged particle formed when an atom loses one or more electrons.
non-metal
An element that typically does not form positive ions.
positive ion
A charged particle formed when an atom loses one or more electrons.
metals
Elements that are typically found on the left side and in the centre of the periodic table, known for forming positive ions.
periodic table
A tabular arrangement of elements organized by increasing atomic number, where metals are located in specific regions.
non-metal
An element that typically does not form positive ions and is found on the right side of the periodic table.
periodic table
A tabular arrangement of elements organized by increasing atomic number, showing trends in properties and grouping metals and non-metals.
metals
Elements that react to form positive ions and typically have high electrical and thermal conductivity.
non-metals
Elements that do not usually form positive ions and often have lower electrical and thermal conductivity compared to metals.
metal
An element that typically reacts to form positive ions.
non-metal
An element that does not usually form positive ions.
electron arrangement
The distribution of electrons in an atom's electron shells, which influences its chemical reactivity.
atomic number
The number of protons in the nucleus of an atom, which determines the element's identity and position in the periodic table.
Group 0
The group in the periodic table that contains noble gases, characterized by having a full outer electron shell.
noble gases
Elements in Group 0 of the periodic table that are unreactive due to their stable electron arrangements.
noble gases
Elements in Group 0 of the periodic table that are characterized by having a full outer electron shell, making them unreactive.
stable electron arrangement
An electron configuration where the outer shell of an atom is fully occupied, resulting in low reactivity.
helium
A noble gas with two electrons in its outer shell.
noble gases
Elements in Group 0 that have stable electron arrangements and are generally unreactive.
noble gases
Elements in Group 0 of the periodic table that are unreactive due to their stable electron arrangements.
molecules
Groups of two or more atoms bonded together, which noble gases do not easily form.
noble gases
Elements in Group 0 of the periodic table that are characterized by having a full outer electron shell, making them unreactive.
boiling point trend
The observed increase in boiling points of noble gases as you move down Group 0 in the periodic table.
Group 0 elements
Elements in Group 0 of the periodic table, known as noble gases, which are characterized by having a complete outer electron shell.
trends down Group 0
Patterns observed in the properties of noble gases, such as boiling points, as one moves down the group in the periodic table.
Group 1 elements
Elements in the first column of the periodic table, known as alkali metals.
alkali metals
Highly reactive metals in Group 1 of the periodic table, characterized by having one electron in their outer shell.
Group 1 elements
Elements in the first column of the periodic table, known as alkali metals, that have one electron in their outer shell.
outer shell
The highest energy level of electrons in an atom, which determines the chemical properties of an element.
alkali metals
Elements in Group 1 of the periodic table, characterized by having one electron in their outer shell.
reaction with oxygen
The chemical process that occurs when lithium, sodium, and potassium combine with oxygen, resulting in the formation of metal oxides.
Group 1 elements
Elements in Group 1 of the periodic table, including lithium, sodium, and potassium, known for their reactivity with chlorine and water.
halogen reaction
A chemical reaction involving halogens, such as chlorine, with metals or non-metals to form compounds.
alkali metals
Group 1 elements that react vigorously with water to produce hydrogen gas and a metal hydroxide.
reactivity
The tendency of an element to undergo a chemical reaction, which increases down Group 1 for alkali metals.
Group 1 elements
Elements in Group 1 of the periodic table, including lithium, sodium, and potassium, that have similar chemical properties due to having one electron in their outer shell.
similar chemical properties
The characteristic that Group 1 elements share, resulting from their identical outer electron configuration, leading to similar reactivity and bonding behavior.
Group 1 elements
Elements in Group 1 of the periodic table, including lithium, sodium, and potassium, known for their high reactivity.
reactivity trend
The observed increase in reactivity of Group 1 elements as you move down the group.
Group 1 elements
Elements in Group 1 of the periodic table, including lithium, sodium, and potassium, known for their similar chemical properties and reactivity.
reactivity trend
The pattern observed in Group 1 elements where reactivity increases as you move down the group.
halogens
Group 7 elements that are non-metals and exist as diatomic molecules.
Group 7
The group in the periodic table that contains the halogens, characterized by having seven electrons in their outer shell.
halogens
Elements in Group 7 of the periodic table that have seven electrons in their outer shell.
outer shell electrons
Electrons located in the highest energy level of an atom, which determine its chemical properties.
halogens
Group 7 elements that are non-metals and exist as diatomic molecules.
diatomic molecules
Molecules composed of two atoms, which in the case of halogens are pairs of the same element.
halogen
A non-metal element in Group 7 of the periodic table, known for forming salts with metals.
ionic compound
A compound formed when a metal reacts with a halogen, resulting in the transfer of electrons and formation of ions.
halogen
A non-metal element in Group 7 of the periodic table, known for forming diatomic molecules and having seven electrons in their outer shell.
non-metal compound
A chemical substance formed when halogens react with non-metals, typically resulting in covalent bonds.
relative molecular mass
The mass of a molecule relative to the mass of one twelfth of a carbon-12 atom.
Group 7
The group in the periodic table that contains the halogens, characterized by their diatomic molecular forms and trends in reactivity.
melting point
The temperature at which a solid becomes a liquid.
boiling point
The temperature at which a liquid becomes a gas.
Group 7
A group in the periodic table that contains the halogens, characterized by their reactivity and trends in properties.
reactivity
The tendency of an element to undergo chemical reactions, which decreases down Group 7 due to increasing atomic size and electron shielding.
halogen
A group of elements in Group 7 of the periodic table, known for their reactivity and ability to form salts with metals.
displacement reaction
A chemical reaction where one element replaces another in a compound, particularly observed between halogens and halide salts.
Group 7
A group in the periodic table consisting of halogens, known for their reactivity and trends in properties.
halogens
Elements in Group 7 of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine, characterized by their diatomic molecular forms.
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