Atom Structure: Electron Shells

The video explains how the reactivity of elements is determined by the number and arrangement of electrons in their shells. Electrons move around the nucleus in shells, with each shell holding a specific number of electrons. The outer shell's electron count influences an element's reactivity, as atoms seek stability by filling their outer shells. Potassium, with one outer electron, is reactive, while noble gases like neon and argon are stable due to full outer shells.

What is the maximum number of electrons that the first shell of an atom can hold?

• 2 electrons

• 8 electrons

• 4 electrons

• 6 electrons

How many electrons does a sodium atom have in its outer shell?

• 1 electron

• 2 electrons

• 7 electrons

• 8 electrons

Which element has 9 electrons and 7 in its outer shell?

• Oxygen

• Fluorine

• Neon

• Argon

Why are noble gases like neon and argon unreactive?

• They have no electrons

• They have a full outer shell of electrons

• They have only one electron

• They have an incomplete outer shell

What happens to potassium when it reacts with other elements?

• It gains an electron

• It splits into two atoms

• It remains unchanged

• It loses an electron