Grade 10 chemisty – The Periodic Table Quiz

The modern periodic table is arranged in order of increasing atomic number (number of protons). This arrangement groups elements with similar properties into columns.

A group is a vertical column. Elements in the same group often have similar chemical properties because they have the same number of valence electrons.

Elements in the same group have the same number of electrons in their outermost shell (valence electrons), which determines chemical reactivity and bonding patterns.

Alkali metals react vigorously with water to form a metal hydroxide (alkaline solution) and hydrogen gas, e.g., sodium + water → sodium hydroxide + hydrogen.

Noble gases have complete valence shells (stable electronic configurations), so they have little tendency to gain or lose electrons and are mostly unreactive.

The atomic number equals the number of protons in an atom's nucleus and also equals the number of electrons in a neutral atom.

Mass number is the total count of protons and neutrons in the nucleus; electrons are too light to contribute significantly to mass.

Isotopes have the same number of protons (same element) but different numbers of neutrons, so their mass numbers differ.

The period (row) indicates the highest principal energy level containing electrons for that element (e.g., elements in period 3 have electrons in the third shell).

Across a period, nuclear charge increases while electrons are added to the same shell; the stronger pull from the nucleus draws electrons closer, reducing atomic radius.

Moving down a group adds extra electron shells, so the size of the atom increases despite increased nuclear charge.

Across a period, electrons are held more strongly by the increasing nuclear charge, so more energy is needed to remove an electron (ionisation energy rises).

Fluorine is the most electronegative element; it strongly attracts electrons in a bond. Noble gases like helium do not have a defined electronegativity in normal bonding.

Elements on the left are metallic (lose electrons easily). Moving to the right, atoms hold electrons more strongly and show non-metallic behaviour, so metallic character falls.

Halogens (group 17) have seven valence electrons and gain one electron to achieve a full shell, forming a -1 ion (e.g., Cl-).

Transition metals (d-block) commonly exhibit several oxidation states and their compounds are frequently coloured due to d-electron transitions.

Lanthanides and actinides belong to the f-block and are usually displayed as two separate rows below the main body of the periodic table to keep the table compact.

Sodium donates an electron to chlorine; this transfer creates oppositely charged ions (Na+ and Cl-) that attract each other, forming an ionic bond (e.g., NaCl).

The table shows metals on the left and middle (including transition metals), while non-metals lie on the right side, with a zig-zag line separating them from metals.

Group 2 elements (alkaline earth metals) have two valence electrons and typically form +2 ions, giving a valency of 2.

Noble gases tend to be unreactive and normally have an oxidation state of 0 because their outer shells are full.

Elements in the same group share valence electron configurations, so their chemical reactivity is similar. Position in group is a good predictor of reactivity.

Number of neutrons = mass number − atomic number = 35 − 17 = 18.

Group 15 elements have five electrons in their outermost shell, so they commonly show valency related to five valence electrons (e.g., nitrogen has 5).

Both are carbon (6 protons). Carbon-12 has 6 neutrons, carbon-14 has 8 neutrons; carbon-14 is radioactive because of the extra neutrons.