C1 - atomic structure and the periodic table

• What are all substances made of?

  Atoms
• How small are atoms compared to visible objects?

  Too small to see with the eyes
• How many atoms are estimated to be in a grain of sand?

  About 170 sextillion
• What particles do atoms contain?

  Protons, neutrons, and electrons
• What is the structure of the nucleus in an atom?

  • Located in the middle of the atom
  • Contains protons and neutrons
  • Very small (about 1/100,000 of atom's radius)
  • Has a positive charge due to protons
  • Almost all mass of the atom is in the nucleus
• What charge do electrons have?

  Negative charge
• How do electrons move around the nucleus?

  In selective orbits, shells, or clouds
• What is the relative mass of a proton?

  1
• What is the relative mass of an electron?

  Very small
• Why are atoms neutral?

  Equal number of protons and electrons
• What happens to the charges in an atom?

  Charges cancel out due to equal numbers
• What do atomic number and mass number indicate about an atom?

  • Atomic number: number of protons
  • Mass number: total number of protons and neutrons
  • Neutrons: mass number minus atomic number
• What is the atomic number of sodium?

  11
• What is an ion?

  An atom with an unequal number of protons and electrons
• What is the formula to calculate the number of neutrons?

  Mass number - Atomic number
• What are isotopes?

  • Different forms of the same element
  • Same number of protons but different neutrons
  • Example: Carbon-12 and Carbon-14
• What is the relative atomic mass formula?

  Sum of (isotope mass number × abundance) / total abundance
• How do you calculate the relative atomic mass of copper with isotopes Cu-63 and Cu-65?

  Use their abundances and mass numbers
• What is a compound?

  • Substances formed from two or more elements
  • Atoms joined by chemical bonds
  • Fixed proportions of elements
• What is covalent bonding?

  Atoms share electrons to form molecules
• What is the formula for water?

  H₂O
• How are chemical formulas structured?

  • Represented by elemental symbols
  • Indicate the number of each atom in the compound
  • Brackets indicate groups of atoms
• What is the formula for sulfuric acid?

  H₂SO₄
• What happens to the properties of a compound compared to its elements?

  Properties are usually different
• What are the methods to separate mixtures?

  • Filtration
  • Crystallisation
  • Chromatography
• What is chromatography used for?

  To separate substances in a mixture
• Why shouldn't you use a pen for chromatography?

  Pencil marks are insoluble in solvent
• What is the process of simple distillation?

  • Used to separate solutions
  • Involves heating and condensing
  • Collects the liquid with the lowest boiling point
• What is fractional distillation used for?

  • Separates a mixture of liquids
  • Based on different boiling points
  • Collects liquids at various temperatures
• What did Rutherford's experiment demonstrate?

  Plum pudding model was incorrect
• What does the electron shell model explain?

  How electrons occupy shells around the nucleus
• What are the rules for electron shells?

  1. Electrons occupy shells
  2. Lowest energy levels filled first
  3. Maximum electrons per shell
  4. Full or half-full shells are stable
  5. Outer shell not full leads to reactivity
• How do you determine the electronic structure of an element?

  Follow the electron shell rules
• Why does the deflection of some particles disprove the plum pudding model?

  It shows that atoms have a concentrated nucleus
• What governs the whole of chemistry?

  • Electrons occupy shells around the nucleus
• What are the rules for electron shells?

  1. Electrons occupy shells (energy levels).
  2. Lowest energy levels filled first.
  3. Limited number of electrons per shell.
  4. Full or half-full shells are stable.
  5. Atoms with unfilled outer shells tend to react.
• How many electrons can the first shell hold?

  2 electrons
• How many electrons can the second shell hold?

  8 electrons
• What is the electronic structure of nitrogen (atomic number 7)?

  2, 5
• What is the electronic structure of magnesium (atomic number 12)?


  2, 8, 2