ECAT MCQs

Metallic bonding explains conductivity and malleability.
Valence electrons move through the metal lattice.

A cation forms when electrons are lost.
It has more protons than electrons.

An anion forms when electrons are gained.
It has more electrons than protons.

Rutherford concluded that atoms contain a small dense positive nucleus.
Most atomic volume is empty space.

Atomic number identifies the element.
In a neutral atom it also equals the number of electrons.

Mass number applies to a specific isotope.
It is always a whole number.

Isotopes have the same atomic number but different mass numbers.
Their chemical behavior is usually similar.

Ions form by gaining or losing electrons.
Cations are positive and anions are negative.

Percent composition is calculated from formula mass contributions.
The element percentages sum to approximately 100%.

Stoichiometry uses balanced equations to relate amounts.
It supports mass, mole, particle, and gas calculations.

Moles equal mass divided by molar mass.
18 g ÷ 18 g/mol = 1 mol.

Mass equals moles multiplied by molar mass.
2×58.5 = 117 g.