Elements

• 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 type of atom?

  The number of protons in the nucleus determines the type of atom.
• What is the atomic number of hydrogen?


  1
• What is the atomic number of helium?

  2
• What is the definition of an element in terms of its atomic structure?

  A substance that only contains atoms with the same number of protons is called an element.
• How many different elements are there approximately?

  About 100 different elements.
• What do all atoms of a particular element have in common?

  All atoms of a particular element have the same number 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 are isotopes?

  Isotopes are different forms of the same element that have the same number of protons but a different number of neutrons.
• How do isotopes differ from each other?

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

  Carbon-12 and carbon-13.
• What is the relative atomic mass (A_r) used for?

  Relative atomic mass is used instead of mass number when referring to the element as a whole.
• How is relative atomic mass calculated?

  Relative atomic mass (A_r) = sum of (isotope abundance × isotope mass number) / sum of abundances of all the isotopes.
• Calculate the relative atomic mass of copper with isotopes Cu-63 (69.2% abundance) and Cu-65 (30.8% abundance).

  Relative atomic mass = 63.6
• What are the key differences between atoms, elements, and isotopes?

  • Atoms: Basic units of matter, made up of protons, neutrons, and electrons.
  • Elements: Substances made of atoms with the same number of protons.
  • Isotopes: Variants of elements with the same number of protons but different numbers of neutrons.
• Why is it important to know the differences between atoms, elements, and isotopes?

  Understanding these differences is crucial for studying chemistry and the behavior of matter.
• What is the abundance of Si-28 if silicon has three stable isotopes: Si-28 (92.2%), Si-29 (4.7%), and Si-30 (3.1%)?

  92.2%
• What is the significance of the periodic table in relation to element symbols?

  The periodic table displays the symbols of elements for easy reference.
• What is the mass number of carbon-12?

  12
• What is the mass number of carbon-13?

  13
• How does the number of neutrons affect the mass number of an isotope?

  The mass number of an isotope is the sum of protons and neutrons, so different numbers of neutrons result in different mass numbers.