Electron Configuration + Periodic Table
What is the maximum number of electrons in the second shell of an atom?
8
What type of ion is formed when an atom loses electrons?
A positive ion (called a cation).
When naming ionic compounds, what ending do we add to the name of the non-metal element?
We add “-ide” to the end of the non-metal’s name.
Na+Cl2→NaCl
2Na+Cl2→2NaCl
How does increasing the temperature affect the rate of a chemical reaction?
Increasing temperature makes particles move faster, leading to more frequent and energetic collisions, which increases the reaction rate.
What is the electron configuration of an atom with 11 electrons?
2,8,1
Describe what happens to electrons during the formation of an ionic compound.
Electrons are transferred from the metal atom to the non-metal atom. The metal becomes a cation, and the non-metal becomes an anion.
Give an example of a compound name where the non-metal ends with ‘-ide’.
Sodium chloride, magnesium oxide, etc
Mg+HCl→MgCl2+H2
Mg+2HCl→MgCl2+H2
What role does a catalyst play in a chemical reaction?
A catalyst lowers the activation energy needed, allowing more particles to react faster without being used up in the process.
Which group and period is an element in if it has the electron configuration 2,8,7?
Group 17, Period 3
Magnesium forms Mg²⁺ and fluorine forms F⁻. What is the formula of the compound they make?
MgF₂ – You need 2 F⁻ ions to balance the 2⁺ charge from one Mg²⁺ ion.
What is the name of the compound with the formula Al₂O₃?
Aluminium oxide
Al+CuSO4→Al2(SO4)3+Cu
2Al+3CuSO4→Al2(SO4)3+3Cu
How does increasing the concentration of a reactant affect the rate of reaction?
Higher concentration means more particles in a given volume, leading to more collisions and a faster reaction.
What is a ‘period’ on the periodic table? What does it tell you about the elements?
A row of elements where all atoms have the same number of electron shells.
Aluminium and oxygen are bonding. Write the correct formula for the compound they make.
Al₂O₃ – Two Al³⁺ (total +6) and three O²⁻ (total -6) balance the charges.
What is the name of the compound (NH₄)₂SO₄?
Ammonium sulfate — includes two polyatomic ions.
KOH+H3PO4→K3PO4+H2O
3KOH+H3PO4→K3PO4+3H2O
What is activation energy, and why is it important in chemical reactions?
Activation energy is the minimum amount of energy particles need to collide with to start a chemical reaction. It is important because only collisions with enough energy can break bonds and form new ones, allowing the reaction to occur.
Which group contains elements that are unreactive and why?
Group 18 (noble gases) — because their outer electron shells are full.
Ammonium is a polyatomic ion with the formula NH₄⁺. What is the formula of the compound formed between ammonium and sulfate (SO₄²⁻)?
(NH₄)₂SO₄ – Two ammonium ions (each +1) are needed to balance the -2 charge of one sulfate ion.
What is the name of the compound formed from Fe³⁺ and Cl⁻?
Iron(III) chloride — the (III) shows that iron has a 3+ charge.
Ca3(PO4)2+HCl→CaCl2+H3PO4
Ca3(PO4)2+6HCl→3CaCl2+2H3PO4
Two identical reactions are carried out, one at 30°C and one at 60°C. Explain which reaction is faster, using collision theory and activation energy.
At 60°C, particles have more kinetic energy, so collisions are more frequent and more particles have enough energy to overcome the activation energy barrier, increasing the reaction rate.