The nucleus

• What is an approximation for the radius of an atom?

  1 x 10^-10 metres
• What are the three subatomic constituents of an atom?

  Proton, Neutron, Electron
• Where is most of the mass of an atom concentrated?

  In the nucleus
• Approximately what proportion of the total radius of an atom is the radius of the nucleus?

  1/10,000
• Describe the arrangement of protons, neutrons, and electrons in an atom.

  • Protons and neutrons are found in the atom’s nucleus
  • Electrons are found in discrete energy levels around the nucleus
• What type of charge does the nucleus of an atom have and why?

  Positive charge because it contains protons
• Give two ways that an atom’s electron arrangement can be changed.

  Absorbing or emitting electromagnetic radiation
• How does an atom’s electron arrangement change when it absorbs EM radiation?

  Electrons move to higher energy levels away from the nucleus
• How does an atom’s electron arrangement change when it emits EM radiation?

  Electrons move to a lower energy level towards the nucleus
• What do all forms of the same element have in common?

  The number of protons
• How does the ratio of electrons to protons in an atom result in the atom having no overall charge?

  The number of protons equals the number of electrons, canceling their charges
• What is the name given to the number of protons in an atom?

  Atomic Number
• What is an atom’s mass number?

  The total number of protons and neutrons in the atom
• What is an isotope of an atom?

  An atom of an element that has a different number of neutrons but the same number of protons
• What property differs between isotopes of an element?

  The mass of the atom
• How do atoms turn into positive ions?

  They lose one or more of their outer electrons
• What are the relative masses of a proton, neutron, and electron?

  1 - proton, 1 - neutron, 1/1850 - electron
• What is the relative charge of a proton?

  +1
• What is the relative charge of an electron?

  • 1