atoms and what they are made of

• All substances are made of atoms.
• Atoms contain protons, neutrons and electrons.
• What do atoms contain?

  protons

  neutrons

  electrons
• Atoms have a radius of about what?

  0.1 nanometres
• A nanometre is one billionth of a metre.
• What does the nucleus contain?

  protons

  neutrons
• What charge does the nucleus have?

  positive charge
• What causes the nucleus to have a positive charge?

  protons
• Where is almost the whole of the mass of an atom concentrated?

  the nucleus
• Electrons move around the nucleus in shells or energy levels.
• What charge does an electron have?

  Negative
• What is an electrons relative mass?

  very small, often taken as 0
• Electrons are tiny.
• Electrons cover a lot of space.
• The volume of electrons orbits determine what?

  atom size
• Electrons have virtually no mass.
• What is a protons relative mass?

  1
• What is a neutrons relative mass?

  1
• What is a protons charge?

  +1
• What is a neutrons charge?

  0
• What is an electrons charge?

  -1
• Protons are heavy and positively charged.
• Neutrons are heavy and neutral.
• Electrons are tiny and negatively charged.
• The number or protons is equal to the number of electrons.
• What is equal to the number of protons?


  number of electrons
• Atoms are neutral.
• Atoms are what?


  neutral
• Atoms are neutral because they have the same number of protons as electrons.
• Why are atoms neutral?

  because they have the same number of protons as electrons.
• The charge on electrons is the same size as the charge on the protons but opposite- so the charges cancel out.
• In an ion, number of protons doesn't equal number of electrons.
• An ion is an atom or group of atoms that has gained or lost electrons.
• An ion has an overall charge.
• The nuclear symbol of an atom tells you its atomic (proton) number and mass number.
• Atomic number is equal to what?

  number of protons.
• The atomic number tells you how many protons are ion that atom.
• Mass number tells you what?

  total number of protons and neutrons in an atom.
• Mass number tells you total number of protons and neutrons in an atom.
• To get the number of neutrons in an atom, what do you do?

  subtract atomic number from mass number.