Section 2: Periodic Table Trends & Element Properties
Q1: Which element requires the least energy to give up an electron — Ba, S, Si, or Ca?
✔ Barium (Ba). Ionization energy decreases going DOWN a group and to the LEFT across a period. Ba is in
Group 2, Period 6 — largest atomic radius, lowest ionization energy.
Q2: Based on its location in the periodic table, what can be predicted about sulfur?
✔ Sulfur (Group 16) has SIX valence electrons available for bonding. It typically forms covalent bonds and can
gain 2 electrons to form S²■ .
Q3: Who reported four 'element' classifications but included some compounds as true elements?
✔ Antoine Lavoisier — he compiled an early list of elements but incorrectly included some compounds (like
lime/calx) as elements.
Q4: Which group on the periodic table contains the alkali metals?
✔ Group 1 (except Hydrogen). Alkali metals have 1 valence electron, are highly reactive, and readily form +1
ions.
Q5: What is the general trend for atomic radius across a period (left to right)?
✔ Atomic radius DECREASES left to right across a period because nuclear charge increases while electrons
are added to the same shell, pulling them closer to the nucleus.
Q6: What is the general trend for electronegativity across a period?
✔ Electronegativity INCREASES left to right across a period and DECREASES going down a group. Fluorine
(F) has the highest electronegativity (4.0).
Q7: What is the ratio of Fe ions to O ions in a neutral iron(III) oxide compound?
✔ In Fe ■O ■: Fe³ ■ ions to O² ■ ions = 2 : 3. Formula: Fe ■O ■ (iron(III) oxide).
Section 3: Chemical Bonding — Ionic & Covalent
Q1: Which of the following compounds is ionic? SF■ , HNO■ , MgO, SeCl■ , or SOCl■ ?
✔ MgO — Magnesium oxide is ionic (metal + nonmetal). The others are covalent (nonmetal + nonmetal)
compounds.
Q2: What do Lewis structures help us understand?
✔ Lewis structures show the number of electrons involved in bonding and the arrangement of bonding and
lone-pair electrons around each atom in a molecule.
Q3: What is the difference between an ionic bond and a covalent bond?
✔ Ionic bond: electrons are TRANSFERRED from a metal to a nonmetal, forming oppositely charged ions
(e.g., NaCl).
Covalent bond: electrons are SHARED between two nonmetals (e.g., H■ O, CO■ ).
Q4: Which statement describes a limitation of the kinetic-molecular theory for gases?
✔ The theory ASSUMES that gas particles do not experience intermolecular forces and have negligible
volume — assumptions that break down at high pressure and low temperature.
Q5: What should the IUPAC name for a binary covalent compound lack?
✔ It should lack the names of ions (no '-ide' for the first element). Binary covalent compounds use Greek
prefixes (mono-, di-, tri-) and the second element ends in '-ide'.
Example: N■ O■ = dinitrogen tetroxide.
Q6: What type of intermolecular force is present in all molecules?
✔ London Dispersion Forces (van der Waals forces) — temporary dipoles due to uneven electron distribution.
Present in ALL molecules; stronger in larger, heavier molecules.