True Chemistry

• What is the chemical formula for water?

  H2O
• In the chemical formula for water, there are two hydrogen atoms for every one oxygen
• Atoms are created or destroyed in chemical reactions.

  False
• Steps to balance a chemical equation

  1️⃣ Balance atoms that are only in compounds

  2️⃣ Balance hydrogen atoms

  3️⃣ Balance oxygen atoms

  4️⃣ Check the balance of all atoms
• What type of reaction uses filtration to separate insoluble particles from a liquid?

  Physical
• Crystallization separates a solute from a solution by evaporating the solvent
• Distillation can separate liquids with different boiling points.
• What are the three main states of matter?

  Solid, liquid, gas
• In a solid state, particles vibrate around fixed positions
• Gases can be compressed, but solids and liquids cannot.
• What type of energy is required to overcome electrostatic forces of attraction between particles?

  Heat
• In chemical reaction equations, state symbols indicate the state of the substance
• The symbol 'aq' in a chemical equation indicates that the substance is dissolved in water.
• Steps in the development of atomic theory

  1️⃣ JJ Thomson's plum pudding model

  2️⃣ Ernest Rutherford's discovery of the nucleus

  3️⃣ Neil Bohr's discovery of electron shells

  4️⃣ James Chadwick's discovery of neutrons
• What is the relative mass of a proton?

  1
• Electrons have negligible mass compared to protons.
• The atomic number of an element is the number of protons in its nucleus
• What determines the identity of an element?

  Proton number
• Match the particle with its relative charge:

  Proton ↔️ +1

  Electron ↔️ -1

  Neutron ↔️ 0
• Atoms with the same number of protons but different numbers of neutrons are called isotopes.
• The average relative atomic mass of an element takes into account the relative abundance of its isotopes
• How do you calculate the average relative atomic mass of an element?

  Multiply mass by abundance, add, divide by 100
• Mendeleev grouped elements based on their properties and atomic weights.
• Mendeleev left gaps in his periodic table for undiscovered elements
• What is the maximum number of electrons in the first shell of an atom?

  2
• Electrons fill shells from the inside out.
• What is the electron configuration of magnesium (12 electrons)?

  282
• Metals are located to the left of the staircase on the periodic table, and they always donate electrons
• Match the group of the periodic table with its properties:

  Group 1 ↔️ Alkali metals

  Group 7 ↔️ Halogens

  Group 0 ↔️ Noble gases
• Group 1 metals become more reactive down the group.
• Noble gases are unreactive because they have a full outer shell
• What charge do group 1 ions have?

  1+
• Transition metals can form ions with different charges.
• What are the two possible charges for iron ions?

  2+ and 3+
• Metallic bonding involves a lattice of positive ions surrounded by delocalized electrons
• Metals are good conductors of electricity due to the movement of delocalized electrons.
• What type of bonding occurs between a group 1 metal and a group 7 non-metal?

  Ionic
• In a dot and cross diagram for ionic bonding, only the outer shell is drawn.
• The charges of all ions in an ionic compound must add up to zero.
• What is the chemical formula for barium chloride?

  BaCl2