Atoms

• What are the three subatomic particles that make up an atom?

  Protons, neutrons, and electrons
• What does the prefix "sub" in subatomic particles refer to?

  It refers to the fact that these particles are much smaller than the atoms as a whole
• What is the central part of an atom called?

  The nucleus
• What is the significance of the nuclear model of the atom?

  It acknowledges the existence of the nucleus, which was unknown before this model
• What are the distances from the nucleus where electrons orbit called?

  Shells or energy levels
• What is the relative charge of protons?

  +1
• What is the relative charge of neutrons?

  0 (neutral)
• What is the relative charge of electrons?

  • -1
• Why do atoms have no overall electric charge?

  Because the number of electrons equals the number of protons
• What keeps electrons in orbit around the nucleus?

  Electrostatic attraction between the negatively charged electrons and the positively charged nucleus
• What is the atomic number of an element?

  The number of protons in an atom's nucleus
• How is the atomic number represented in the periodic table?

  As the smaller number, usually shown at the bottom
• What is the atomic number of nitrogen?


  7
• What is the atomic number of oxygen?

  8
• What is the atomic number of hydrogen?

  1
• What does the nucleus of an atom contain?

  Protons and neutrons
• What is the radius of an atom approximately?

  About $0.1 \text{ nm} =$$1 \times 10^{-10} \text{ m}$
• How does the radius of the nucleus compare to the radius of the atom?

  The nucleus is about $\frac{1}{10,000}$th of the radius of the atom
• What is the relative mass of protons and neutrons?

  Both have a relative mass of 1
• How many electrons would it take to balance the mass of one proton?

  Nearly 2,000 electrons
• What is the mass number of an atom?

  The sum of the number of protons and neutrons
• How is the atomic number represented in the periodic table?

  As the smaller number
• How do you calculate the number of neutrons in an atom?

  By subtracting the atomic number from the mass number
• If sodium has an atomic number of 11 and a mass number of 23, how many neutrons does it have?

  12 neutrons
• For lithium with an atomic number of 3 and a mass number of 7, how many neutrons does it have?

  4 neutrons
• For fluorine with an atomic number of 9 and a mass number of 19, how many neutrons does it have?

  10 neutrons
• For oxygen with an atomic number of 8 and a mass number of 16, how many neutrons does it have?

  8 neutrons
• What are isotopes?


  Atoms of the same element with different numbers of neutrons
• How are isotopes usually named?

  Using their mass number as a reference point
• For chlorine-35, what is its atomic number and how many neutrons does it have?

  Atomic number 17 and 18 neutrons
• For chlorine-37, what is its atomic number and how many neutrons does it have?

  Atomic number 17 and 20 neutrons
• How do atoms become ions?

  By losing or gaining electrons
• What happens to an atom's charge when it gains an electron?

  It becomes more negative
• What happens to an atom's charge when it loses an electron?

  It becomes more positive
• What does electronic structure refer to?

  How the electrons are arranged in an atom
• What are the energy levels or shells in an atom?

  Regions where electrons are found, shown as circles around the nucleus
• Why do electrons occupy the lowest available energy level?

  To achieve the most stable arrangement for the atom
• How many elements do you need to work with for GCSE chemistry?

  The first 20 elements
• What is the maximum capacity of the first shell in an atom?

  2 electrons
• What is the maximum capacity of the second shell in an atom?

  8 electrons