Atomic structure, Isotopes and Electron shells

• What charge do protons have?

  Positive charge
• What is the relative mass of protons and neutrons?

  One
• How much smaller are electrons compared to protons or neutrons?

  About two thousand times smaller
• What is the charge of an electron?

  Negative charge
• What is each box in the periodic table called?

  Nucleus symbol
• What does the atomic number represent?

  Number of protons in an atom
• Why is the atomic number important for identifying elements?

  It determines which element it is
• What does the mass number indicate?

  Total number of protons and neutrons
• What are isotopes?

  Atoms with the same protons but different neutrons
• What happens to unstable isotopes?

  They decay into other elements by emitting radiation
• What is the process called when unstable isotopes decay?

  Radioactive decay
• What do electrons in an atom occupy?

  Energy levels called shells
• What happens when electrons gain enough energy?

  They can jump to a higher energy level
• What is an excited electron?

  An electron that has gained energy
• What provides the energy for an electron to jump energy levels?

  Electromagnetic radiation
• What happens after an electron falls back to a lower energy level?

  It re-emits energy as electromagnetic radiation
• What is ionization?

  When an electron leaves the atom completely
• What charge does an atom have after ionization?

  Positive charge
• What does ionizing radiation do?

  It can knock electrons off atoms