TBT 2 The Atom

Which of the following is an example of an anion?

• Na⁺¹

• H₂O⁻¹

• Ca⁺²

• Cl⁻¹

The atomic number of an element represents:

• The number of neutrons

• The number of electrons

• The number of protons

• The sum of protons and neutrons

What are valence electrons?

• Electrons in the outermost shell

• Electrons in the nucleus

• Electrons with negative charge

• Electrons in the innermost shell

What is the octet rule in chemistry?

• Atoms always have exactly 8 electrons in their outermost shell

• Atoms tend to gain or lose electrons to have 8 valence electrons

• Only noble gases follow the octet rule

• The octet rule applies to all elements without exception

What is the main feature of Bohr's atomic model?

• Protons move freely around the nucleus

• Neutrons are found outside the nucleus

• Energy is absorbed by the atom

• Electrons orbit the nucleus in fixed energy levels

The electron cloud model suggests that electrons:

• Have fixed positions around the nucleus

• Are found in a probability distribution around the nucleus

• Are always in the outermost shell

• Do not move at all

What is an isotope?

• An atom with a different number of protons

• An atom with a different number of electrons

• An atom with a different number of neutrons

• A completely different element

The mass number of an atom is equal to:

• The number of protons

• The number of protons plus neutrons

• The number of electrons

• The number of neutrons minus protons

What is an ion?

• A neutral atom

• An atom with an equal number of protons and electrons

• A molecule with a shared electron pair

• An atom with an unequal number of protons and electrons

A cation is formed when an atom:

• Gains electrons

• Loses electrons

• Gains protons

• Loses protons