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?

  H2O
• How many hydrogen atoms are in one molecule of water?

  There are two hydrogen atoms in one molecule of water
• What happens to atoms during a chemical reaction?

  Atoms change what they're bonded to and how they're bonded through chemical reactions
• What is a word equation?

  A word equation represents a chemical reaction using the names of the reactants and products
• 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 present on both sides
• What is the first step in balancing a chemical equation?

  Start balancing atoms that are only in compounds
• How do you balance hydrogen atoms in a chemical equation?

  By placing a coefficient in front of the compound containing hydrogen to multiply the number of hydrogen atoms
• What is a mixture?

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

  Air, which is a mixture of oxygen, nitrogen, and more
• What is filtration used for?

  Filtration is used to separate large insoluble particles from a liquid
• What is crystallization?

  Crystallization is a process that leaves a solute behind after evaporating the solvent from a solution
• What is distillation?

  Distillation involves heating a solution to separate components based on their boiling points
• What is fractional distillation?

  Fractional distillation is a method to separate different liquids in a mixture based on their different 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 in a solid
• How do particles behave in a gas state?

  Particles are far apart and move randomly with high energy in a gas
• What is required to melt or evaporate a substance?

  Energy, usually in the form of heat, is required to overcome the electrostatic forces of attraction between particles
• What are state symbols used for 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
• 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?

  Nucleons
• What is the charge of a proton?

  The charge of a proton is +1
• What is the charge of a neutron?

  The charge of a neutron is 0
• What is the atomic number of an element?

  The atomic number is the number of protons in the nucleus
• What does the mass number represent?

  The mass number represents 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
• What is relative atomic mass (RAM)?

  Relative atomic mass is the weighted average mass of an element's isotopes compared to carbon-12
• How is the average relative atomic mass calculated?

  By adding the total masses of all isotopes and dividing by the total number of atoms
• What was the early periodic table based on?

  The early periodic table was based on the atomic weights of elements
• Who is credited with creating a more modern periodic table?

  Dmitri Mendeleev
• How are elements grouped in the periodic table?

  Elements are grouped based on their properties and similar characteristics
• What is the maximum number of electrons in the first four shells of an atom?

  2 in the first shell, 8 in the second and third shells, and 2 in the fourth shell
• What are the properties of metals in the periodic table?

  Metals donate electrons to achieve a full outer shell
• What are the properties of nonmetals in the periodic table?

  Nonmetals accept electrons to achieve a full outer shell
• What does the group number in the periodic table indicate?

  The group number indicates how many electrons are in the outer shell of an atom
• What are alkali metals?

  Alkali metals are in group one and have one electron in their outer shell
• How does reactivity change in alkali metals as you move down the group?

  Reactivity increases as you move down the group
• What are halogens?

  Halogens are in group seven and have seven electrons in their outer shell