atoms, isotopes, ions

• What are the three main subatomic particles in an atom?

  Protons, neutrons, and electrons
• What is the approximate radius of an atom?

  1 × 10^-10 metres
• What does the modern view of the atom consist of?

  A nucleus containing protons and neutrons with electrons orbiting outside
• Describe the Bohr atomic model.

  It has three neutrons and three protons in the center with two energy levels
• What is the relative charge and mass of a neutron?

  Relative charge 0, relative mass 1
• What is the relative charge and mass of a proton?

  Relative charge +1, relative mass 1
• What is the relative charge and mass of an electron?

  Relative charge -1, relative mass close to 0 (1/2000)
• What defines an element?

  The number of protons in its nucleus
• Why do protons and neutrons make up most of the mass of an atom?

  Because they are the heaviest particles in an atom
• What is the atomic number of an atom?

  The number of protons in the nucleus
• What is the mass number of an atom?

  The total number of protons and neutrons
• What happens to the number of electrons in an ionized atom?

  The number of electrons changes
• How can an atom become a positively charged ion?

  By losing one or more electrons
• What is an ion?

  An atom that has lost or gained one or more electrons
• How can an atom become a negatively charged ion?

  By gaining one or more electrons
• How many protons does the chlorine atom with mass number 35 have?

  17 protons
• What does the symbol notation for an atom represent?

  Mass number (A), atomic number (Z), and symbol (X)
• What are isotopes?

  • Forms of an element with the same number of protons
  • Different numbers of neutrons
• How many isotopes of hydrogen are there?

  Three isotopes
• What are the names of the three isotopes of hydrogen?

  Hydrogen, deuterium, and tritium
• How many neutrons does chlorine with mass number 37 have?

  20 neutrons
• How many protons does 146C contain?

  Six protons
• Why are 147N and 146C not isotopes of each other?

  They are not the same element due to different numbers of protons
• What happens to an atom when it gains an electron?

  It becomes a negatively charged ion
• What is the charge of a neutral atom?

  It has no charge
• What happens to an atom when it loses an electron?

  It becomes a positively charged ion
• How many electrons does a neutral helium atom have?

  Two electrons
• What is the charge of a helium ion that has lost an electron?

  It is a positive ion
• What is the charge of a helium ion that has gained an electron?

  It is a negative ion