Elements

• What is the smallest particle of an element?


  Atom
• What surrounds the nucleus of an atom?


  Electrons
• What is a molecule?


  A particle that consists of two or more atoms chemically bonded together
• How is an element defined?


  A substance made of only one type of atom that can't be broken down
• What is a compound?


  A substance made of two or more elements chemically combined
• Give an example of a compound.


  HCl
• What is a mixture?


  A mixture contains two or more substances not chemically combined together
• Provide an example of a mixture.

  Air
• What are isotopes?


  Forms of an element that have the same number of protons but different numbers of neutrons
• How is relative atomic mass calculated?


  By adding up all the masses of isotopes in an element
• If an element has isotopes with masses of 10 and 11, and abundances of 20% and 80% respectively, what is the relative atomic mass?


  $10.8$
• How do you calculate the relative atomic mass using the given isotopes and their abundances?


  Use the formula: $X =$ \frac{(10 \times 20) + (11 \times 80)}{100}
• What is an element?


  An element is a substance made up of atoms that all have the same number of protons in their nucleus.
• What determines the identity of an element?


  The number of protons in the nucleus determines what element it is.
• How many different elements are there approximately?


  There are about 100 different elements.
• What is the definition of an element in terms of its atomic structure?


  An element is a substance that only contains atoms with the same number of protons.
• How do atoms of different elements differ?


  Different elements have atoms with different numbers of protons.
• How can atoms of each element be represented?


  Atoms of each element can be represented by a one or two letter symbol.
• What is the purpose of using symbols for elements?


  Symbols save you the bother of having to write the full name of the element.
• What is the symbol for carbon?


  C
• What is the symbol for oxygen?


  O
• What is the symbol for sodium?


  Na
• What are isotopes?


  Isotopes are different forms of the same element with the same number of protons but different numbers of neutrons.
• How do isotopes differ in terms of atomic and mass numbers?


  Isotopes have the same atomic number but different mass numbers.
• What are the isotopes of carbon mentioned in the material?


  Carbon-12 and carbon-13.
• What is the atomic structure of Carbon-12?


  Carbon-12 has 6 protons, 6 electrons, and 6 neutrons.
• What is the atomic structure of Carbon-13?


  Carbon-13 has 6 protons, 6 electrons, and 7 neutrons.
• Why is relative atomic mass used instead of mass number?


  Relative atomic mass is used because many elements can exist as different isotopes.
• What does relative atomic mass take into account?


  Relative atomic mass takes into account the different masses and abundances of all the isotopes that make up the element.
• What is the formula for calculating relative atomic mass?


  Relative atomic mass = sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes.
• How do you calculate the relative atomic mass of copper given its isotopes Cu-63 and Cu-65?


  Relative atomic mass = (69.2 × 63) + (30.8 × 65) / 100.
• What is the relative atomic mass of copper calculated from its isotopes?


  The relative atomic mass of copper is 63.6.
• What is the significance of isotopes in chemistry?


  • Isotopes are different forms of the same element.
  • They have the same number of protons but different numbers of neutrons.
  • They affect the relative atomic mass of elements.
• What is the difference between an element and a substance with varying neutron counts?


  • An element consists of atoms with the same number of protons.
  • A substance with varying neutron counts can have different isotopes but remains the same element.
• What are the stable isotopes of silicon and their abundances?


  • Si-28: 92.2%
  • Si-29: 4.7%
  • Si-30: 3.1%