Chemistry paper 1

• What is a compound?

  A compound is a substance that contains two or more different types of atoms chemically bonded together
• What is the chemical formula for water?

  The chemical formula for water is H₂O
• How do we represent a chemical reaction?

  A chemical reaction can be represented with a word equation and a chemical equation using symbols
• Why must chemical equations be balanced?

  Because atoms are not created or destroyed in a chemical reaction, the same number of each type of atom must be on both sides
• What is the first step in balancing a chemical equation?

  Start balancing atoms that are only in compounds
• What is a mixture?

  A mixture is any combination of different types of elements and compounds that aren't chemically bonded together
• What is an example of a mixture?

  Air is a mixture of oxygen, nitrogen, and more
• How can large insoluble particles be separated from a liquid?

  By using filtration
• What is crystallization used for?

  To separate a solute from a solvent after evaporating the solvent
• What is distillation?

  Distillation involves heating a solution and cooling the gas to condense it back into a liquid
• What is fractional distillation?

  Fractional distillation separates different liquids in a mixture based on their boiling points
• What are the three main states of matter?

  Solid, liquid, and gas
• How do particles behave in a solid state?

  Particles vibrate around fixed positions
• What happens to particles when a substance melts or evaporates?

  Energy is supplied to overcome the electrostatic forces of attraction between the particles
• What do state symbols indicate in chemical equations?

  State symbols indicate the physical state of substances: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous
• Who proposed the plum pudding model of the atom?

  JJ Thompson proposed the plum pudding model of the atom
• What did Ernest Rutherford discover about the atom?

  He discovered that the positive charge is concentrated in a small nucleus
• What did Niels Bohr contribute to atomic theory?

  Niels Bohr discovered that electrons exist in shells or orbitals around the nucleus
• What are protons and neutrons collectively called?

  Protons and neutrons are collectively called nucleons
• What does the atomic number represent?

  The atomic number represents the number of protons in the nucleus
• What is the charge of a proton and an electron?

  Protons have a charge of +1 and electrons have a charge of -1
• What happens when an atom gains or loses electrons?

  It becomes an ion, not an atom
• What does the mass number indicate?

  The mass number indicates the total number of protons and neutrons in the nucleus
• What are isotopes?

  Isotopes are atoms of the same element with different numbers of neutrons
• How is the average relative atomic mass calculated?

  By considering the relative abundance of each isotope
• What did Dmitri Mendeleev contribute to the periodic table?

  Dmitri Mendeleev grouped elements based on their properties, even if the order didn't follow atomic weight
• How are electrons arranged in an atom?

  Electrons are arranged in shells around the nucleus
• What is the maximum number of electrons in the first four shells?

  The maximum number of electrons is 2 in the first shell, 8 in the second and third shells, and 2 in the fourth shell
• What are the properties of metals?

  Metals donate electrons to gain an empty outer shell and are good conductors of electricity and heat
• What are the properties of nonmetals?

  Nonmetals accept electrons to gain a full outer shell
• What is the reactivity trend in group 1 elements?

  Reactivity increases as you go down the group
• What is the reactivity trend in group 7 elements?

  Reactivity decreases as you go down the group
• What are noble gases known for?

  Noble gases are known for being very unreactive
• What happens to metals when they lose electrons?

  They become positively charged ions
• What is the charge of ions formed by group 1 and group 2 metals?

  Group 1 metals form +1 ions and group 2 metals form +2 ions
• What is the charge of ions formed by group 7 and group 6 nonmetals?

  Group 7 nonmetals form -1 ions and group 6 nonmetals form -2 ions
• What is ionic bonding?

  Ionic bonding occurs when a metal atom loses electrons and a non-metal atom gains electrons
• What must the charges of all ions in an ionic compound add up to?

  The charges must add up to zero
• What is the structure of ionic compounds?

  Ionic compounds consist of repeating units of ions in a lattice structure
• What are the properties of ionic compounds?

  Ionic compounds have high melting and boiling points and can conduct electricity when molten or dissolved