chem

• 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
• What topics are covered in AQA GCC chemistry paper 1?

  Topics 1 to 5: atoms, bonding, quantitative chemistry, and chemical energy changes
• How many hydrogen atoms are in one molecule of water?

  There are two hydrogen atoms in one molecule of water
• What does it mean if there is no number after a chemical symbol?

  It indicates there is an invisible one
• What must be true about the number of atoms in a chemical reaction?

  The same number of each type of atom must be present on both sides of the equation
• What is the first step in balancing a chemical equation?

  Start balancing atoms that are only in compounds
• Why do we put numbers in front of elements or compounds when balancing equations?

  To multiply the number of atoms without changing the compound's identity
• 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, which is a mixture of oxygen and nitrogen
• How can you separate large insoluble particles from a liquid?

  Using filtration
• What is crystallization used for?

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

  Heating a solution to separate components based on boiling points
• What is fractional distillation?

  A method to separate 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 water when it is in a gas state?

  Water vapor particles are far apart and move randomly
• What is required to melt or evaporate a substance?

  Energy, usually in the form of heat
• What do state symbols indicate in chemical equations?

  They indicate the state of substances: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous
• Who discovered that atoms are made up of positive and negative charges?

  JJ Thompson
• What is the plum pudding model of the atom?

  A model where positive charge is spread out with electrons dotted around
• Who discovered the nucleus of the atom?

  Ernest Rutherford
• What did Neil's Bohr discover about electrons?

  Electrons exist in shells or orbitals around the nucleus
• What are protons and neutrons collectively called?

  Nucleons
• What is the charge of a proton?

  +1
• What is the charge of a neutron?

  0
• What is the relative mass of protons and neutrons?

  Both have a relative mass of 1
• What is the relative mass of electrons?

  Electrons have a relative mass of 0 or very small
• What does the atomic number represent?

  The number of protons in the nucleus
• What does the mass number indicate?

  It tells you how many protons and neutrons are in the nucleus
• What are isotopes?

  Atoms of the same element with different numbers of neutrons
• What is relative abundance?

  The percentage of each isotope present in a sample
• How do you calculate the average relative atomic mass?

  Add the total masses of all isotopes and divide by the total number of atoms
• How was the periodic table originally organized?

  Elements were ordered by their atomic weights
• Who grouped elements based on their properties rather than atomic weight?

  Dmitri Mendeleev
• What is the maximum number of electrons in the first four shells?

  2 in the first, 8 in the second, 8 in the third, and 2 in the fourth
• What do metals do with their outer electrons?

  Metals donate their outer electrons to achieve a full outer shell
• What do nonmetals do with their outer electrons?

  Nonmetals accept electrons to achieve a full outer shell
• What is the group number of an atom related to?

  It indicates how many electrons are in the outer shell
• What are the properties of alkali metals?

  They have one electron in their outer shell and are highly reactive