Chemistry Isotopes Quiz

Atomic Structure

• Protons and neutrons are found in the nucleus of an atom.
• Electrons are found in energy levels (shells) around the nucleus.
• The number of protons in an atom determines the element.
• The number of electrons in an atom can vary, leading to ions.

Isotopes

• Isotopes are atoms of the same element with different numbers of neutrons.
• Examples: 12C, 13C, 14C; 35Cl, 37Cl.

Ions

• Positive ions have lost electrons.
• Negative ions have gained electrons.
• Examples: Na+ (11 protons, 12 neutrons, 10 electrons); F- (9 protons, 10 neutrons, 10 electrons).

Relative Atomic Mass

• The relative atomic mass is the weighted average of the mass numbers of different isotopes.
• It is calculated based on the abundance of each isotope.
• Formula: (mass number of isotope 1 x percentage abundance of isotope 1) + (mass number of isotope 2 x percentage abundance of isotope 2) + ... / 100.

Electron Energy Levels

• The number of electrons in the outer energy level determines the group number of an element in the periodic table.
• Each energy level (shell) can hold a maximum number of electrons: 2 in the first shell, 8 in the second shell, 8 in the third shell, and 18 in the fourth shell.

Noble Gases

• The noble gases are very unreactive elements.
• They have a full outer energy level.
• Examples: He, Ne, Ar, Kr, Xe, Rn.
• The boiling points of noble gases increase with their relative atomic masses.
• The boiling points of noble gases are all lower than room temperature.