model of atom

• What are the building blocks of matter?

  Atoms
• What are atoms made of?

  Atoms are made of subatomic particles called protons, neutrons, and electrons.
• Where are protons and neutrons located in an atom?


  In the nucleus
• How do electrons move in an atom?


  Electrons move very fast around the nucleus in orbital paths called shells.
• Why is the mass of an electron considered negligible?


  Because the mass of an atom is contained within the nucleus where the protons and neutrons are located.
• What is the smallest part of an element that retains its properties?

  The atom
• What is a chemical symbol?


  A chemical symbol represents an element and is unique to that element.
• How many elements are commonly found on the Periodic Table?


  Around 103 to 118 elements
• What is the significance of the first letter in a two-letter chemical symbol?


  The first letter is always written in uppercase letters.
• Which elements exist as diatomic molecules in nature?


  H, N, O, F, Cl, Br, and I
• What does the atomic number represent?


  The number of protons in an atom.
• What is a compound?


  A compound is a pure substance made up of two or more elements chemically combined.
• How are compounds formed?


  Compounds are formed when elements take part in chemical reactions and combine in fixed ratios.
• What is the chemical formula for water?


  H₂O
• What is the difference between pure substances and mixtures?


  Pure substances contain only one element or compound, while mixtures contain two or more different substances.
• What are the properties of compounds compared to the elements that form them?


  • Compounds usually have different properties from the elements that form them.
  • They cannot be separated by physical means.
• How do you name ionic compounds?


  The metal element's symbol is written first, and the non-metal takes the name ending ‘–ide’ unless oxygen is present.
• What is the naming convention for compounds containing oxygen?


  When oxygen is present, the name ending is usually ‘-ate’.
• What is the difference between ‘-ite’ and ‘-ate’ in compound naming?


  The ending ‘-ite’ has less oxygen than ‘-ate’.
• How are covalent compounds named?


  Covalent compounds are named using prefixes (mono, di, tri, tetra, penta) to indicate the number of each element present.
• What is the common name for H₂SO₄?


  Sulfuric acid
• What do word equations represent in chemistry?


  Word equations show the reactants and products of a chemical reaction using their full chemical names.
• What is the format of a word equation?

  Reactants → Products
• What do the reactants in a word equation represent?


  Reactants are the substances on the left-hand side of the arrow.
• What does the arrow in a word equation imply?


  The arrow implies the conversion of reactants into products.
• What is an example of a word equation?

  Sodium hydroxide + Hydrochloric acid → Sodium chloride + Water
• What are the steps to write balanced equations?

  1. Ensure reactants are on the left and products on the right.
  2. Write non-metals as molecules.
  3. Include state symbols (s), (l), (g), (aq).
  4. Balance the equation to have equal numbers of each atom on both sides.
• What is the Law of Conservation of Mass?


  It states that the same number of atoms must be present on both sides of a balanced equation.
• What is an example of a balanced symbol equation?


  2Al (s) + 3CuO (s) ⟶ Al₂O₃ (s) + 3Cu (s)
• How do you balance an equation?


  You work across the equation from left to right, checking one element after another.
• What is the first step in balancing a chemical equation?


  Balance elements that appear on their own last in the process.
• What are the common examples of balanced symbol equations?

  • Acid-base neutralisation: NaOH (aq) + HCl (aq) ⟶ NaCl (aq) + H₂O (l)
  • Redox reaction: 2Fe₂O₃ (aq) + 3C (s) ⟶ 4Fe (s) + 3CO (g)
• What is the unbalanced symbol equation for the reaction between aluminium oxide and copper oxide?


  _Al (s) + _CuO (s) ⟶ _Al O (s) + _Cu (s)
• What is the balanced symbol equation for the reaction between aluminium and copper oxide?


  2Al (s) + 3CuO (s) ⟶ Al O (s) + 3Cu (s)
• How do you balance the aluminium atoms in the reaction?


  By ensuring there are 2 aluminium atoms on the reactant side.
• How do you balance the oxygen atoms in the reaction?


  By using 3 CuO on the reactant side to match the 3 oxygen atoms on the product side.
• What is the final balanced equation after balancing copper atoms?


  2Al + 3CuO ⟶ Al O + 3Cu
• What is the unbalanced equation for the reaction of magnesium oxide with nitric acid?

  MgO + HNO ⟶ Mg(NO ) + H O
• What is the balanced symbol equation for the reaction of magnesium oxide with nitric acid?


  MgO (s) + 2HNO (aq) ⟶ Mg(NO ) (aq) + H O (l)
• How do you balance the hydrogen atoms in the reaction of magnesium oxide with nitric acid?


  By using 2 HNO on the reactant side to match the 2 hydrogen atoms on the product side.