Atoms

• What are all things made up of, including living and non-living organisms?

  Atoms
• How many atoms are estimated to be in a single cell?

  More than 100 trillion
• What is the basic structure of an atom?

  A central nucleus surrounded by electrons in shells
• What are the two types of particles that make up the nucleus of an atom?

  Protons and neutrons
• What is the relative mass of protons and neutrons?

  One
• How much smaller is the mass of an electron compared to protons and neutrons?


  Two thousand times smaller
• What charge do protons have?

  Positive charge (+1)
• What charge do neutrons have?

  No charge (neutral)
• What charge do electrons have?

  Negative charge (-1)
• How can you remember the charges of protons, neutrons, and electrons?

  Protons are positive, neutrons are neutral, and electrons are negative
• What is the typical radius of an atom?

  Around 0.1 nanometers
• What is mostly found in an atom?

  Empty space
• How does the size of the nucleus compare to the size of the atom?

  The nucleus is 10,000 times smaller than the atom
• What happens to an atom when it gains or loses electrons?

  It becomes an ion
• What is a negative ion?

  An atom with more electrons than protons
• How do you denote a one minus negative ion?

  By having one extra electron
• What is a positive ion?

  An atom with more protons than electrons
• What does the periodic table represent?

  Different types of atoms called elements
• What does the elemental symbol represent?


  The one or two letter symbol for an element
• What does the atomic number indicate?

  The number of protons in an atom
• How do you find the number of neutrons in an atom?

  Mass number minus atomic number
• How many electrons does an atom have if the number of protons is equal to the atomic number?

  The same number as the protons
• What are the key components of an atom's structure?

  • Central nucleus
  • Protons and neutrons in the nucleus
  • Electrons orbiting in shells
• What are the charges and relative masses of protons, neutrons, and electrons?

  • Protons: +1 charge, relative mass of 1
  • Neutrons: 0 charge, relative mass of 1
  • Electrons: -1 charge, relative mass of 1/2000
• How do ions differ from neutral atoms?

  • Ions have an unequal number of protons and electrons
  • Positive ions have more protons than electrons
  • Negative ions have more electrons than protons
• What information does the periodic table provide about elements?

  • Elemental symbol
  • Atomic number (number of protons)
  • Mass number (total number of protons and neutrons)