The Periodic Table (AQA GCSE Combined Science: Synergy: Physical Sciences): Flashcards

Metals are found on the left and towards the bottom of the periodic table. Most elements are metals.

True.

Metals lose their outer electrons to form positive ions (cations). Non-metals gain electrons to form negative ions (anions). This difference in behaviour underlies their distinct chemical properties.

Metallic character decreases moving from left to right across a period, and increases moving down a group.

A Group 7 non-metal forms a 1- ion (e.g. Cl^-). Its outer shell needs only one more electron to become full, so it is easier to gain one electron than to lose seven.

A non-metal is an element found on the right and towards the top of the periodic table. Non-metals typically form negative ions by gaining electrons, are poor electrical conductors, and form acidic oxides.

False.

Reactivity decreases going down Group 7, but the reason is that the outer shell is further from the nucleus, so there is less attraction towards an incoming electron, making it harder to gain an electron, not easier.

Metals are lustrous (shiny) and malleable (can be bent and shaped). Non-metals are typically dull and brittle/flaky. Metals also have higher melting points than most non-metals.

True.

Metal oxides are basic (they react with acids). Most non-metal oxides are acidic (though some are neutral). This is a key chemical distinction between metals and non-metals.

The noble gases are the elements in Group 0 of the periodic table. They are unreactive, monatomic, colourless, non-flammable gases at room temperature with full outer shells of electrons.

The noble gases have full outer shells of electrons (8 electrons, except helium which has 2). A full outer shell is a stable arrangement, so they do not need to lose, gain, or share electrons to react.

False.

Most noble gases have 8 electrons in their outer shell, but helium is an exception — it has only 2 electrons, which still gives it a full and stable outer shell.

The boiling points of the noble gases increase going down Group 0, because the atoms get larger and their relative atomic mass increases, leading to stronger forces between atoms.

Argon is used to provide an inert atmosphere during welding, preventing unwanted reactions with oxygen and other gases in the air. It is also used to fill light bulbs.

Monatomic means existing as single atoms rather than as molecules. The noble gases are monatomic because their full outer shells mean they have no tendency to bond with other atoms.

False.

All noble gases have very low boiling points, all below 0 °C. Helium has the lowest boiling point of any known element (–269 °C), and even radon, the heaviest common noble gas, boils at around –60 °C.

Going down Group 0, atoms have a greater relative atomic mass and are larger. This leads to stronger intermolecular forces between atoms, so more energy is needed to overcome them and reach the boiling point.

True.

The noble gases occupy Group 0, which is the last group on the far right of the periodic table.

The alkali metals are the Group 1 elements. They are soft, have low melting points and low densities, and are very reactive because they each have one electron in their outer shell.

An alkali metal reacts with water to produce a metal hydroxide and hydrogen gas. For example: 2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g)

True.

Going down Group 1, the outer electron is further from the nucleus and held less strongly. Less energy is needed to remove it, so the metals become more reactive going down the group.

Alkali metals are stored in oil to prevent them reacting with oxygen or water vapour in the air.

Going down Group 1, atoms have more electron shells, so the outer electron is further from the nucleus. The force of attraction between the nucleus and the outer electron is weaker, so less energy is needed to remove it.

The Group 1 reactivity trend describes how reactivity increases going down the group. Each successive element has more electron shells, placing the outer electron further from the nucleus and reducing the attraction needed to remove it.

False.

The melting points of Group 1 metals decrease going down the group. This is due to decreasing attractive forces between outer electrons and positive ions as the atoms get larger.

True.

Group 1 metals have low densities. Lithium, sodium and potassium are all less dense than water, so they float on the surface during their reactions with water.

True.

Alkali metals lose their one outer electron to form 1+ ions. When they react with non-metals (e.g. oxygen or chlorine), the resulting compounds are ionic (e.g. Li₂O, NaCl).

The halogens are the elements in Group 7 of the periodic table. They are non-metals with 7 electrons in their outer shell, and they exist as diatomic molecules.

False.

Reactivity decreases going down Group 7. The atoms have more electron shells, so the outer shell is further from the nucleus and it is harder to gain an electron.

Properties of the halogens at room temperature:

Going down the group, the atoms become larger so the intermolecular forces between the molecules increase. More energy is needed to overcome these stronger forces, resulting in higher boiling points.

A halide ion is a halogen atom that has gained one electron to form a 1- ion, such as Cl^- or Br^-.

False.

Halogen molecules are diatomic, meaning they contain two atoms, but they are joined by a single covalent bond, not an ionic bond.

A halogen displacement reaction occurs when a more reactive halogen replaces a less reactive halogen from a solution of its halide.

Going down the group, atoms have more electron shells. The outer shell is further from the nucleus, so the attraction between the nucleus and an incoming electron is weaker. This makes it harder to gain an electron.

True.

Chlorine is above bromine in Group 7 and is more reactive. Chlorine displaces the bromide ions, turning the solution orange.

Results of halogen displacement reactions: