The Periodic Table/Periodic Trends
What are valence electrons?
Valence electrons are the outermost electrons of an atom that are involved in chemical bonding.
What must be the same on both sides of a balanced chemical equation
The number of each type of atom.
What type of reaction is 2H₂ + O₂ → 2H₂O?
Synthesis reaction.
What does Boyle’s Law state about pressure and volume?
As pressure increases, volume decreases (inverse relationship), assuming constant temperature.
What is the difference between kinetic and potential energy?
Kinetic energy is energy of motion; potential energy is stored energy.
Which element has a larger atomic radius: sodium (Na) or chlorine (Cl)?
Sodium (Na), because atomic radius decreases across a period.
Balance the equation: Na + Cl₂ → NaCl
2Na + Cl₂ → 2NaCl
What type of reaction is 2KClO₃ → 2KCl + 3O₂?
Decomposition reaction.
According to Charles’ Law, what happens to the volume of a gas when the temperature increases and the pressure stays the same?
The volume increases when the temperature increases, as long as the pressure stays the same.
What is the definition of activation energy
energy required to start a reaction
What happens to ionization energy as you move from left to right across a period?
Ionization energy increases because the nuclear charge increases, pulling electrons closer.
What is the balanced equation for Ca(OH)₂ + HCl → CaCl₂ + H₂O?
Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O
Identify the type of reaction: Zn + CuSO₄ → ZnSO₄ + Cu
Single replacement reaction.
If a gas has a pressure of 2.0 atm and volume of 4.0 L, what is the new volume if the pressure increases to 4.0 atm (Boyle’s Law)?
2.0 L
How many joules are in 10.0 calories? (1 cal = 4.184 J)
41.84 joules
Why does atomic radius decrease as you move across a period from left to right on the periodic table?
Because more protons are added to the nucleus, increasing the positive charge, which pulls electrons closer to the nucleus, making the atom smaller.
Balance the equation: C₂H₆ + O₂ → CO₂ + H₂O
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
What are the products of a complete combustion reaction of a hydrocarbon?
Carbon dioxide (CO₂) and water (H₂O).
What are two parts of kinetic molecular theory?.
1. Gas particles are in constant, random motion.
A 50g sample of water is heated from 20°C to 80°C. How much energy is required? (specific heat of water = 4.18 J/g°C)
Q = mcΔT = 50 × 4.18 × 60 = 12,540 J
How does shielding affect the trend of ionization energy as you move down a group on the periodic table?
As you move down a group, more electron shells are added, increasing shielding. This reduces the attraction between the nucleus and the outer electrons, so ionization energy decreases.
Balance the equation: C₇H₁₆ + O₂ → CO₂ + H₂O
C₇H₁₆ + 11O₂ → 7CO₂ + 8H₂O
What happens in a synthesis reaction, and what happens in a decomposition reaction?
In a synthesis reaction, two or more substances combine to form one product.
In a decomposition reaction, one compound breaks down into two or more simpler substances.
A gas occupies 300 mL at 25°C. What will its volume be at 75°C? (change to kelvin)
350 ML
What do the variables of Q = mcΔT mean
q: heat energy (joules), m: mass (grams), c: specific heat (J/g༝c°), ΔT: change in temperature (°c)