Intro & Atomic Structure
What’s the difference between a physical and chemical change?
A physical change doesn’t change the substance’s identity; a chemical change does.
What does the column number on a periodic table tell you?
The number of valence electrons.
Identify the type of reaction: Na + Cl₂ → NaCl.
Synthesis.
Name three states of matter and give one property of each.
Solid (definite shape), liquid (flows), gas (compressible).
Answers may vary for properties!
Define exothermic and endothermic.
Exothermic releases heat; endothermic absorbs heat.
Name three subatomic particles and their charges.
Proton (+), neutron (0), electron (−).
What type of bonds form between metals and nonmetals?
Ionic bonds.
Define the term “mole ratio.”
The ratio of coefficients in a balanced equation.
What happens to gas volume when temperature increases (at constant pressure)?
Volume increases.
What is activation energy?
The minimum energy needed to start a reaction.
What is the Aufbau principle in electron configuration?
Electrons fill the lowest energy orbitals first.
Compare polar and nonpolar covalent bonds.
Polar bonds share electrons unequally; nonpolar share equally.
How many grams are in 3 moles of CO₂?
132 grams. (CO₂ = 44 g/mol × 3)
What’s the molarity of a solution made by dissolving 5 moles of salt in 2 L of water?
2.5 M
Use q = mcΔT where m = 100g, c = 4.18 J/g°C, ΔT = 15°C.
q = 6,270 J
How many atoms are in 2.0 moles of an element?
1.204 × 10²⁴ atoms.
Rank the intermolecular forces (IMFs) from weakest to strongest.
London dispersion < dipole-dipole < hydrogen bonding.
Balance the equation: Al + O₂ → Al₂O₃
4Al + 3O₂ → 2Al₂O₃
A gas has a volume of 10L at 1 atm. What volume will it occupy at 2 atm?
5 L
Name two ways to increase reaction rate and how they help.
Increase temperature (more collisions); add a catalyst (lowers activation energy).