Paper 1

• Chemistry is the study of the elements, which are known to exist.
• An atom is a very, very small thing, named after the Greek word for uncuttable.
• The periodic table is a list of all the elements, known to exist, with information about their range, location, and properties.
• A compound is two or more elements that are chemically bonded together.
• The structure of an atom consists of electrons on the outer shells, protons in the nucleus, and neutrons in the nucleus.
• On the periodic table, the atomic number is the number of protons and electrons in an atom, while the mass number is the number of protons and neutrons.
• To find the number of protons in an element, simply subtract the atomic number from the mass number.
• Liquids have more movement around, but they are not in a fixed position, they can float, but they cannot be compressed.
• Going from a gas to a liquid, we are condensing, going from a liquid to a solid, we are freezing.
• Solids have a very, very thick structure, their atoms may wiggle a little bit, but they are around a fixed point.
• A compound has a melting point of 19 degrees, melting point, and a boiling point of 74, boiling point.
• High boiling points or high melting points are going to be at the bottom.
• Things that have a low boiling point or a low melting point are going to be at the top.
• Alkaline metals want to lose an electron, and the ones at the bottom are most reactive because there is more shielding between the atom they want to use and the positive nucleus in the middle.
• Gases are very, very free to move, there is a lot of movement going on in here, they are not around a fixed position, they can float and they can be compressed.
• Boiling point is going to change as we move down the group.
• Going from a solid to a liquid is melting, from a liquid to a gas is evaporating.
• To find the number of electrons in an element, subtract the atomic number from the mass number.
• To find the number of neutrons in an element, subtract the atomic number from the mass number.
• To balance a chemical equation, draw a line down the middle, circle everything, and list what you have.
• Melting point is when a substance turns from a solid to a liquid.
• Metals are made up of positive atoms in a sea of delocalized electrons, which is why they can conduct electricity and heat so well.
• Carbon, Hydrogen, Oxygen, is an example of covalent bonding.
• Ionic bonding is a transfer of electrons from a metal to a nonmetal.
• Boiling point is equal to condensing point and melting point is equal to freezing point.
• Methane, CH4, is an example of covalent bonding.
• Chlorine, Cl2, is an example of covalent bonding.
• Above room temperature, a substance is a gas, and below room temperature, it is a liquid.
• Nitrogen, N2, is an example of covalent bonding.
• Hydrogen, H2, is an example of covalent bonding.
• Covalent bonding is the sharing of electrons between two nonmetals.
• Ammonia, NH3, is an example of covalent bonding.
• State symbols indicate the state of a substance, such as s for solid, l for liquid, aq for aqueous, and g for gas.
• Oxygen, O2, is an example of covalent bonding.
• In covalent bonding, each line represents a pair of electrons.
• Hydrogen chloride, or hydrogen gas and chlorine gas, is an example of covalent bonding.
• Room temperature is about 25 or 27, so when a substance boils, it turns from a liquid into a gas.
• Things above carbon need electrolysis to be extracted, whereas things below carbon can just be extracted by reduction.
• The formula for the equation of hydrogen peroxide decomposing into water and oxygen gas is 2 hydrogen peroxides making 2 water and 1 oxygen.
• A mole is the unit for the amount of a substance, which is equal to 6 times 10 to the 23 atoms, ions, or molecules.