Chemistry C1

• What is the relative charge of a proton?

  +1
• What is the relative mass of a neutron?


  1
• How is the atomic number defined?

  It equals the number of protons
• What is the relative charge of an electron?

  −1
• What is the relative mass of an electron?

  Very small, considered 0
• Why do atoms have no overall charge?

  Equal numbers of protons and electrons
• What are elements made of?

  One type of atom
• What defines a compound?

  Different types of atoms chemically bonded
• What is a mixture?

  Two or more substances not chemically combined
• How can substances in a mixture be separated?

  Using physical processes
• What are the methods for separating mixtures?

  • Filtration
  • Crystallisation
  • Simple distillation
  • Fractional distillation
  • Paper chromatography
• What are isotopes?

  Atoms of the same element with different neutrons
• How is relative atomic mass calculated?

  Average mass of all isotopes of an element
• What is the maximum number of electrons in the first shell?

  2
• How many electrons can the second and third shells hold?

  Eight each
• What did Dalton's model propose about atoms?

  Atoms are solid spheres that can't be divided
• What did the nuclear model suggest about electrons?

  Electrons orbit the nucleus but not at set distances
• What is the radius of an atom?

  $1 \times 10^{-10} \text{ m}$
• How much smaller are nuclei compared to atoms?

  About 10,000 times smaller
• What did Niels Bohr calculate about electron orbits?

  Electrons orbit at fixed distances
• What is the charge of a proton?

  Opposite to an electron
• What did James Chadwick discover?

  The neutron, a particle with no charge
• What were the steps of the alpha scattering experiment?

  1. Alpha particles fired at gold foil
  2. Expected to pass straight through
  3. Some bounced back and deflected
  4. Led to the conclusion of a concentrated nucleus
• What is the relative mass of protons and neutrons?

  Both have a relative mass of 1
• How many electrons equal the mass of one proton?

  Almost 2000 electrons
• What was the plum pudding model of the atom?

  A cloud of positive charge with electrons embedded
• What led to the discovery of the plum pudding model?

  The discovery of electrons as charged particles