Chapter 2: Atoms and Molecules - Study Guide
Atoms and Molecules – Review Questions
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Anything that has mass and takes up space.
Protons, neutrons, and electrons.
Protons and neutrons.
Protons (atomic number).
It defines the number of protons in an element and determines its identity.
A positively charged particle in the nucleus.
A neutral particle in the nucleus that contributes to atomic mass.
A negatively charged particle that orbits the nucleus.
Electromagnetic (electrostatic) force between protons and electrons.
The strong nuclear force.
Ions.
Isotopes.
The outermost electron shell of an atom that determines its chemical reactivity.
Protons: 13, Neutrons: 14, Electrons: 13, Electron shells: 3, Valence electrons: 3.
Filled shells are unreactive; partially filled outermost shells are reactive.
Elements in the same group (column) because they have the same number of valence electrons.
Gain, lose, or share electrons to complete its valence shell.
The outermost shell (valence shell).
1st shell: 2, 2nd shell: 8, 3rd shell: 18 (octet rule commonly 8).
When its valence shell is full.
Noble gases (group 18) with full valence shells.
Reactants are the starting substances; products are the substances formed.
Endothermic absorbs energy; exothermic releases energy.
Atoms that lose electrons: cations (positive), gain electrons: anions (negative).
Cations: few valence electrons (usually 1–3), anions: almost full valence electrons (usually 5–7).
Boron: 3 reactive; Carbon: 4 reactive; Nitrogen: 5 reactive.
Single bond: one shared electron pair; double bond: two shared electron pairs.
A covalent bond where electrons are shared unequally, creating partial charges.
The more electronegative atom pulls electrons closer, becoming slightly negative, while the other becomes slightly positive.
Polar covalent: electrons shared unequally; ionic: electrons transferred completely.
Polar covalent bonds.
Hydrogen bonding between molecules keeps water cohesive.
Hydrogen bonds form a lattice structure, making solid water less dense than liquid water.
Water has high heat capacity, moderating temperature.
Evaporation of water removes heat from the body.
It is polar and can dissolve many ionic and polar molecules.
Water molecules surround ions, separating and dissolving them.
Water molecules form hydrogen bonds with the polar molecule, allowing it to dissolve.
Carbon forms four covalent bonds, allowing complex, stable, and versatile molecules (organic compounds).