Physical: Atomic structure & bonding

The mass number represents the total number of protons and neutrons in an atom's nucleus, as these particles contribute nearly all of the atom's mass. Option A is incorrect because the atomic number refers solely to the number of protons, which determines the element's identity.

A coordinate covalent bond occurs when one atom provides both electrons for a shared pair, typically from a lone pair. Option A is incorrect because a standard double covalent bond involves each atom sharing an equal number of electrons, typically one or two from each partner.

The mass number represents the total number of protons and neutrons in an atom's nucleus, as these particles contribute nearly all of the atom's mass. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Option A is incorrect because the atomic number refers solely to the number of protons, which determines the element's identity.
• !Option A is incorrect because a standard double covalent bond involves each atom sharing an equal number of electrons, typically one or two from each partner.

Answer each from memory — you'll see instantly whether you're right and why.

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