Atoms, elements and compounds

• What do chemists use to represent elements and compounds?

  Chemical symbols and formulae
• What do word equations and balanced chemical equations represent?

  The changes that happen in chemical reactions
• What is the smallest part of an element that can exist?

  • An atom
• What is an element?

  A substance made of one type of atom only
• How are atoms of each element represented?

  By their own chemical symbol
• What does a chemical symbol consist of?

  One or two letters
• How does a chemical symbol start?

  With a capital letter, followed by lower case letters
• What is the chemical symbol for oxygen?

  O
• What is the chemical symbol for sodium?

  Na
• Why must the chemical symbol of sodium be written as Na?

  Because it must start with a capital letter and any other letter in lower case
• How many different elements are there?

  Over 100
• Where are the names and symbols of the elements shown?

  In the periodic table
• How are elements arranged in the periodic table?

  Into groups with similar properties
• How are groups in the periodic table numbered?

  From 1 to 7, then 0
• Where are metals located in the periodic table?

  On the left of the stepped line
• Where are non-metals located in the periodic table?

  On the right of the stepped line
• What does each box in the periodic table show?

  • The chemical symbol for an element
• What do chemists use to represent elements and compounds?

  Symbols and formulae
• What do word equations and balanced chemical equations represent?

  The changes that happen in chemical reactions
• What is a chemical formula?

  • A combination of symbols
  • Indicates the chemical composition of a substance
• What is an element?

  A substance made of one type of atom only
• What is a compound?

  A substance formed by the chemical union of two or more elements
• What is a balanced chemical equation?

  • A chemical equation using symbols and formulae
  • The number of units of each element is the same on both sides of the arrow
• What is the formula for most elements?

  Its chemical symbol
• What is the chemical symbol for helium?


  He
• What is the chemical symbol for lithium?

  Li
• What is the chemical symbol for beryllium?

  Be
• What is the chemical symbol for boron?

  B
• What is the chemical symbol for carbon?

  C
• What is the chemical symbol for neon?

  Ne
• What is the chemical symbol for sodium?

  Na
• What is the chemical symbol for magnesium?

  Mg
• Which elements are important to remember their symbols for the first 20 elements in the periodic table?

  • Elements in groups 1 and 7
  • First 20 elements in the periodic table
• What do some non-metal elements exist as?

  Molecules made up of two atoms joined together
• What is the formula for iodine?

  I₂
• What is the formula for bromine?

  Br₂
• What is the formula for chlorine?

  Cl₂
• What is the formula for fluorine?

  F₂
• What is the formula for oxygen?

  O₂
• What is the formula for nitrogen?

  N₂