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Metals and Non-metals

Compare the properties of metals with those of non-metals.

  • Define and explain Metals and Non-metals in your own words
  • Use key terms such as group accurately
  • Apply what you have learned to new examples and questions
  • Avoid the common mistakes learners make with this topic

This lesson focuses on Metals and Non-metals: compare the properties of metals with those of non-metals.

Definition: Metals and Non-metals

Compare the properties of metals with those of non-metals.

Key ideas

Metals and non-metals sit on opposite sides

Metals occupy the left and centre of the table, while non-metals sit to the right, separated by a zig-zag line of metalloids. This split mirrors their properties: metals lose electrons to form positive ions, while non-metals tend to gain or share electrons. Knowing which side an element is on lets you predict how it will react.

Position predicts electron arrangement

Elements are arranged in order of increasing atomic number, and this order creates the pattern of groups and periods. The group number tells you the number of outer-shell electrons (for the main groups), and the period number tells you the number of shells. That is why all Group 1 elements have one outer electron and react in similar ways.

Key term — group: A vertical column of the periodic table; elements in the same group have similar properties.

Worked example: Metals and Non-metals

Explain why sodium and potassium have similar chemical properties.

Both are in Group 1, so both have one electron in their outer shell, which they lose in similar reactions.

Answer: Both are in Group 1, so both have one electron in their outer shell, which they lose in similar reactions.

Common mistakes
  • Assuming all metals behave identically Reactivity varies hugely: potassium reacts violently with water while copper does not react at all. Position in the table gives trends, but the trend itself is what you must learn.
  • Reading the group number as the total electrons The group number gives the number of outer-shell electrons, not the total. Chlorine in Group 7 has 7 outer electrons, but 17 electrons in total.

Practice

An element is dull, brittle and does not conduct electricity. Is it a metal or a non-metal? Where does it sit in the table?
Which side of the zig-zag line?

A non-metal; non-metals sit to the right of the table.

Why did Mendeleev leave gaps in his periodic table?
What did the pattern tell him was missing?

The pattern of properties showed that undiscovered elements must exist to fill the gaps, so he left spaces and even predicted their properties.

Fluorine is in Group 7, Period 2. Give its electron arrangement.
Period = shells, group = outer electrons.

2,7.

Lithium, sodium and potassium are dropped into water. Put them in order of vigour of reaction, least vigorous first.
How does Group 1 reactivity change down the group?

Lithium, then sodium, then potassium — reactivity increases down Group 1.

Quick check

Metals and Non-metals — quick check

Which of these best defines "group"?

A vertical column of the periodic table; elements in the same group have similar properties.

Astatine sits below iodine in Group 7. Predict whether it is more or less reactive than iodine, with a reason.

Less reactive: its outer shell is further from the nucleus, so it gains an electron less easily.
Key takeaways
  • Metals and Non-metals: compare the properties of metals with those of non-metals.
  • Metals and non-metals sit on opposite sides: Metals occupy the left and centre of the table, while non-metals sit to the right, separated by a zig-zag line of metalloids.
  • metal: An element that is typically shiny, conducts heat and electricity, and is malleable.
  • Watch out for: assuming all metals behave identically
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