The Periodic Table (Edexcel IGCSE Science (Double Award): Chemistry): Flashcards

The electronic configuration of sodium is 2,8,1. It has 2 electrons in the first shell, 8 in the second and 1 in the third.

Potassium (atomic number 19) has the electronic configuration 2,8,8,1 because the fourth shell begins to fill once the third shell reaches 8 electrons.

The number of occupied electron shells in the electronic configuration equals the period number. For example, chlorine (2,8,7) has 3 occupied shells, so it is in Period 3.

The last number in the electronic configuration gives the number of outer shell electrons, which is the same as the group number. For example, chlorine (2,8,7) has 7 outer electrons, so it is in Group 7. The exception is Group 0 (noble gases), which have a full outer shell (2 for helium, 8 for the others).

True.

Having the same number of outer shell electrons means elements in the same group react and bond in similar ways, giving them similar chemical properties.

Carbon has atomic number 6, so its electronic configuration is 2,4 and it belongs to Group 4 of the Periodic Table.

Shells closer to the nucleus have lower energy. Electrons always occupy the lowest available energy level first, so the first shell fills before the second, and the second before the third.

Metals are elements that are good conductors of electricity, typically solid and lustrous at room temperature, malleable, and form basic oxides. They are found on the left of the Periodic Table.

False.

Metals form basic oxides and non-metals form acidic oxides (some non-metal oxides are neutral). This difference in oxide character is one way to classify an element.

Metals are good conductors of electricity because they have free electrons that can carry charge. Non-metals are poor conductors of electricity as they lack free electrons.

In the Periodic Table, metals are found on the left side and non-metals on the right side, separated by a zig-zag line.

Elements bordering the dividing line are called semi-metals or metalloids because they display characteristics of both metals and non-metals.

True.

Non-metals have 4–7 outer shell electrons. They tend to gain or share electrons to achieve a full outer shell, leading to covalent bonding.

Metals typically have 1–3 outer shell electrons and form metallic bonds by delocalising electrons.

The majority of elements are metals because most elements have relatively few outer shell electrons (1–3) and sit on the left and centre of the Periodic Table. Non-metals occupy only the upper right region.

Noble gases are the elements in Group 0 of the Periodic Table. They are colourless, non-flammable, monatomic gases at room temperature that do not readily react because they have full outer electron shells.

Elements in the same group have the same number of outer shell electrons. Because reactivity and bonding depend on outer electrons, elements in the same group react in similar ways.

True.

Noble gases in Group 0 have full outer shells, so they have no tendency to gain, lose or share electrons. This makes them chemically inert.

Lithium, sodium and potassium are all in Group 1 and become more reactive as you move down the group.

Because all Group 1 elements have one outer electron, they react in similar ways. Observing one reaction lets you predict that others will react the same way, and comparing two or more allows you to establish a trend in reactivity down the group.

False.

Group 7 elements become less reactive moving down the group. This contrasts with Group 1 elements, which become more reactive moving down.

Noble gases are described as inert because they have full outer shells and do not form molecules easily.

Helium is in Group 0 because its only shell, the first shell, is full at 2 electrons. Like all noble gases, it has a full outer shell and is therefore unreactive.