GCSE Chemistry
The Periodic Table Flashcards
30 periodic table terms and trends every GCSE Chemistry paper expects you to define
30 cards~8 min
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All 30 GCSE Chemistry The Periodic Table flashcards
The full deck in writing, listed A to Z. Read it through if the topic is new, then use the cards above to test yourself without looking.
- Alkali Metals
- The elements of Group 1: soft, low-density metals with one outer electron that react vigorously with water and oxygen, so they are stored under oil to stop them oxidising.For example: Lithium, sodium and potassium all fizz, and can even ignite, when dropped into water.
- Atomic Number
- The number of protons in the nucleus of an atom, which also equals the number of electrons in a neutral atom and fixes which element it is.For example: Every atom with atomic number 6 is carbon, whatever its number of neutrons.
- Atomic Radius Trend
- The pattern in atom size: radius increases going down a group as extra electron shells are added, and decreases going across a period as extra protons pull the same-shell electrons in tighter.For example: A potassium atom is measurably larger than a sodium atom, one row above it.
- Chemical Symbol
- A one- or two-letter abbreviation representing an element, with the first letter always capitalised and any second letter always written in lower case.For example: Sodium's symbol is Na, taken from its Latin name natrium rather than its English name.
- Diatomic Molecule
- A molecule made of exactly two atoms bonded together, the natural form taken by each of the halogens at room temperature and pressure.For example: Chlorine exists as Cl2, not as separate single chlorine atoms.
- Electron Shell
- An energy level surrounding an atom's nucleus that can hold a fixed maximum number of electrons before the next shell out starts to fill.For example: The first shell holds up to 2 electrons; the second and third each hold up to 8.
- Electronic Configuration
- The arrangement of an atom's electrons across its shells, written as a series of numbers separated by commas starting from the innermost shell.For example: Sodium's electronic configuration is 2,8,1.
- Group
- A vertical column of the periodic table. Elements in the same group have the same number of electrons in their outer shell, giving them similar chemical properties.For example: Every Group 1 element has one outer electron and reacts in a similar way with water.
- Group 1 + Water Reaction
- The reaction of an alkali metal with water, producing a dissolved metal hydroxide and hydrogen gas, often seen as fizzing, movement across the surface, or a lilac or orange flame.For example: Sodium reacting with water: 2Na + 2H2O gives 2NaOH + H2.
- Group 1 Reactivity Trend
- The pattern that alkali metals become more reactive going down the group, because the single outer electron sits further from the nucleus and is held less tightly, so it is lost more easily.For example: Potassium reacts far more violently with water than lithium does.
- Group 7 Reactivity Trend
- The pattern that halogens become less reactive going down the group, because a larger atom makes it harder for the nucleus to pull one more electron into a now-distant outer shell.For example: Fluorine is the most reactive halogen tested at GCSE; iodine is the least.
- Halogen Displacement Reaction
- A reaction in which a more reactive halogen takes the place of a less reactive halogen inside a dissolved metal halide, providing direct evidence for the Group 7 reactivity trend.For example: Chlorine displaces bromine from potassium bromide solution, turning the colourless solution orange.
- Halogens
- The elements of Group 7: non-metals that exist as pairs of atoms bonded together, and that become less reactive going down the group as the outer shell gets further from the nucleus.For example: Chlorine, bromine and iodine are all halogens with the formula X2.
- Ionisation Energy
- The energy needed to remove one electron from an atom in the gas state, which generally falls going down a group as the outer electron sits further from the attracting nucleus.For example: Sodium has a lower first ionisation energy than lithium, directly above it in Group 1.
- Isotope
- One of two or more atoms of the same element that have the same number of protons but a different number of neutrons, giving them different mass numbers.For example: Carbon-12 and carbon-14 are both isotopes of carbon.
- Mass Number
- The total number of protons and neutrons in an atom's nucleus, used to identify a specific isotope of an element rather than the element in general.For example: Carbon-14 has a mass number of 14: 6 protons plus 8 neutrons.
- Mendeleev's Periodic Table
- The 1869 arrangement by Dmitri Mendeleev that ordered elements by atomic mass and deliberately left gaps for undiscovered elements, correctly predicting their properties in advance.For example: Mendeleev's gap for 'eka-silicon' was later filled by germanium, matching his predicted properties closely.
- Metal-Nonmetal Divide
- The zigzag line running through the periodic table separating metals, on the left and centre, from non-metals, on the upper right, with metalloids sitting close to the line.For example: Silicon, sitting right next to the divide, shares some properties with both metals and non-metals.
- Metallic Character Trend
- The tendency of elements to behave like metals, which increases moving down a group and decreases moving left to right across a period.For example: Carbon, at the top of its group, is a non-metal; tin, lower in the same group, is a metal.
- Neutron
- A particle carrying no electric charge, found in the nucleus alongside protons, that adds to an atom's mass without affecting its charge or which element it is.For example: Changing only the neutron count of an atom produces a different isotope of the same element.
- Newlands' Law of Octaves
- An earlier 1865 attempt by John Newlands to order elements by atomic mass, noticing similar properties repeating every eighth element, but the pattern broke down after calcium and was dismissed at the time.For example: Newlands placed iron in the same group as oxygen and sulfur, a mismatch scientists rejected as clearly wrong.
- Noble Gases
- The elements of Group 0, each with a complete outer shell of electrons, which makes them extremely unreactive under normal laboratory conditions.For example: Helium and neon are both used inside lighting because they will not react with the hot filament.
- Period
- A horizontal row of the periodic table. Moving across a period from left to right, atoms gain one proton and one extra outer-shell electron for each step, without gaining a new shell.For example: Period 3 runs from sodium on the far left to argon on the far right.
- Period 3 Elements
- The eight elements from sodium to argon, which shift from reactive metal, through reactive non-metal, to unreactive gas as atomic number increases across the row.For example: Sodium is a soft reactive metal; argon, two rows later, is an inert gas.
- Proton
- A positively charged particle found in the nucleus of an atom, whose total count sets the atomic number and therefore the element's identity.For example: Any atom containing exactly 8 protons is an atom of oxygen.
- Relative Atomic Mass
- The average mass of an element's naturally occurring atoms, weighted by how common each isotope is, measured against one-twelfth the mass of a carbon-12 atom.For example: Chlorine's relative atomic mass of 35.5 reflects a natural mixture of chlorine-35 and chlorine-37 atoms.
- The Periodic Table
- A chart that arranges all known chemical elements in order of increasing atomic number, grouped so elements with similar chemical properties line up in the same vertical column.For example: Sodium and potassium sit in the same column because both react vigorously with water.
- Transition Metals
- The block of metallic elements between Group 2 and Group 3, typically dense with high melting points, forming coloured compounds and sometimes several different ion charges.For example: Iron can form Fe2+ or Fe3+ ions depending on the compound it is part of.
- Uses of Noble Gases
- Practical applications of Group 0 elements that rely on their lack of reactivity, including filling light bulbs and providing an unreactive atmosphere for welding.For example: Argon fills incandescent bulbs to stop the hot filament reacting with oxygen in the air.
- Valence Electron
- An electron in an atom's outermost occupied shell, the electrons directly involved in forming chemical bonds and in determining how reactive an element is.For example: Chlorine has seven valence electrons, one short of a full outer shell.