Atoms

• What is an atom?

  Smallest part of an element
• What is Dalton's model of the atom?

  Atoms as solid spheres that could not be divided into smaller parts
• What is the plum pudding model of the atom?

  Sphere of positive charge with negative electrons embedded in it
• What is an atom?

  Smallest part of an element that can exist
• What is Dalton's model of the atom?

  Atoms as solid spheres that could not be divided
• What is the plum pudding model of the atom?

  Sphere of positive charge with negative electrons embedded
• What did scientists discover in the alpha scattering experiment?

  Some alpha particles were deflected by gold foil, shows that an atom is mostly empty space and is concentrated in the nucleus
• Describe the nuclear model of the atom.

  Dense nucleus with electrons orbiting it
• What did Niels Bohr discover?

  Electrons orbit in fixed shells (energy levels)
• What did James Chadwick discover?

  Uncharged particle called the neutron
• Where are protons and neutrons located?

  In the nucleus
• What is the relative mass of each sub-atomic particle?

  Proton: 1 Neutron: 1 Electron: 0
• What is the relative charge of each sub-atomic particle?

  Proton: +1 Neutron: 0 Electron: -1
• How can you find out the number of protons in an atom?

  By looking at the atomic number
• How can you calculate the number of neutrons in an atom?

  Mass number - atomic number
• Why do atoms have no overall charge?

  Equal numbers of positive protons and negative electrons
• How many electrons would you place in the first shell?

  Up to 2 electrons
• How many electrons would you place in the second shell?

  Up to 8 electrons
• How many electrons would you place in the third shell?

  Up to 8 electrons
• What is an element?

  Substance made of one type of atom
• What is a compound?

  Substance made of more than one type of atom chemically joined
• What is a mixture?

  Two or more substances not chemically combined
• What are isotopes?

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

  The average mass of all atoms of an element