GCSE Atomic Structure & Periodic Table 5

Question 1

Mendeleev left gaps in his periodic table. Why was this considered a strength of his model?

Accepted Answer

The gaps successfully predicted properties of undiscovered elements

Answer

Mendeleev predicted elements like gallium and germanium, which were later discovered with properties matching his predictions.

Question 2

Which of the following best explains why atoms are electrically neutral?

Accepted Answer

They contain equal numbers of protons and electrons

Answer

Protons carry +1 and electrons carry −1; equal numbers of each result in a net charge of zero.

Question 3

Element Q has the electron arrangement 2,8,6. In which group and period is it found?

Accepted Answer

Group 6, Period 3

Answer

Period = number of occupied shells (3), Group = outer electrons (6), so Group 6, Period 3 — sulfur.

Question 4

As you move down Group 1, the melting points of the alkali metals:

Accepted Answer

Decrease

Answer

Melting points decrease down Group 1 as atomic radius increases and metallic bonding becomes weaker.

Question 5

A fluorine atom has 9 protons. A fluoride ion (F⁻) has:

Accepted Answer

10 electrons

Answer

Fluorine gains 1 electron to form F⁻, so it has 9 protons and 10 electrons.

GCSE - General Certificate of Secondary Education Practice Test