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Periodic Table · Chapter 1

Metallic and
non-metallic character

The direction an atom prefers: giving away its outer electrons, or collecting electrons to complete its outer shell.

Metallic characterlose electron(s) → positive ion → reducing behaviour
Non-metallic charactergain electron(s) → negative ion → oxidising behaviour

By the end of this lesson you can

  1. define metallic and non-metallic character;
  2. explain how atomic size and nuclear charge affect each;
  3. state the trends across a period and down a group;
  4. arrange elements in the correct order of character; and
  5. connect electron loss or gain with reducing and oxidising agents.
01

Metallic character: electrons leave

Metals do not merely look shiny. In this chapter, their important behaviour is their tendency to lose their outermost electrons.

Metallic character is the tendency of an atom to lose one or more valence electrons and form a positive ion.

Sodium

Na: 2, 8, 1
Na → Na⁺ + e⁻
Na⁺: 2, 8

One outer electron is relatively easy to give away, so sodium has metallic character.

Magnesium

Mg: 2, 8, 2
Mg → Mg²⁺ + 2e⁻

It loses two valence electrons and forms a positive ion, so it too is metallic.

Think of a nearly empty outer hand: it is easier to give away one or two loosely held objects than to keep holding them.

What controls it?

Larger atom → outer electron farther from nucleus → weaker attraction → electron lost more easily → greater metallic character
Greater nuclear charge → stronger attraction for electrons → electron harder to remove → lower metallic character
03

Non-metallic character: electrons arrive

An atom with a nearly full outer shell may find it easier to collect one, two or three electrons than to empty the shell.

Non-metallic character is the tendency of an atom to gain electrons, complete its outermost shell and form a negative ion.

Chlorine

Cl: 2, 8, 7
Cl + e⁻ → Cl⁻
Cl⁻: 2, 8, 8

It needs one electron to complete its outer shell.

Oxygen

O: 2, 6
O + 2e⁻ → O²⁻

It gains two electrons and forms a negative ion.

Valence electronsElectrons usually gainedExample
53Nitrogen-type arrangement
62Oxygen
71Chlorine

A smaller atom attracts an incoming electron more strongly because its outer shell is closer to the nucleus. Greater nuclear charge also increases this attraction. So smaller size and greater nuclear pull favour non-metallic character.

05

Trend explorer

Tap a route. The blue bars show metallic character; the green bars show non-metallic character. The exact height is a visual comparison, not a measured value.

Which route are you travelling?

left of periodright of period

Preview
Across Period 3, oxide nature changes broadly from basic (Na₂O, MgO) through amphoteric (Al₂O₃) to acidic (SiO₂, P₂O₅, SO₃, Cl₂O₇). This connects with the change from metallic to non-metallic character; the oxide topic is developed later.
06

How to compare two elements

Four quick steps

  1. Find their relationship: same period or same group?
  2. Across: remember metallic ↓ and non-metallic ↑.
  3. Down: remember metallic ↑ and non-metallic ↓.
  4. Give the reason: atomic size and nuclear attraction.
Worked example 1 — sodium or magnesium: which is more metallic?
Both are in Period 3. Metallic character decreases from left to right. Sodium is to the left of magnesium, so sodium is more metallic than magnesium.
Worked example 2 — sulphur or chlorine: which is more non-metallic?
Both are in Period 3. Non-metallic character increases from left to right. Chlorine is more non-metallic than sulphur.
Worked example 3 — lithium or caesium: which is more metallic?
Both are in Group 1. Metallic character increases down a group. Caesium is more metallic than lithium.
Worked example 4 — fluorine or chlorine: which is more non-metallic?
Both are in Group 17. Non-metallic character decreases down a group. Fluorine is more non-metallic than chlorine.
Worked example 5 — arrange Na, Mg, Al, Si in increasing metallic character
Across Period 3, metallic character decreases left to right. Therefore Si < Al < Mg < Na.
Worked example 6 — arrange C, Si, Ge, Sn in decreasing non-metallic character
Non-metallic character decreases down Group 14. Therefore C > Si > Ge > Sn.
07

Check your understanding

Your score records questions you answer yourself. Revealed answers do not score.

· 1 of 17

Metallic character is the tendency to:

A metal tends to lose valence electrons and form a positive ion.
· 2 of 17

Across a period, metallic character:

Across a period, nuclear pull increases and size decreases; metallic character decreases.
· 3 of 17

Down a group, non-metallic character:

Additional shells make the atom larger, weakening attraction for an incoming electron.
· 4 of 17

Which element is more non-metallic?

In Period 3 non-metallic character increases towards chlorine.
· 5 of 17

What type of ion does a metal form?

A metal forms a positive ion (cation).
· 6 of 17

What type of ion does a non-metal form?

A non-metal forms a negative ion (anion).
· 7 of 17

A metal acts as a reducing agent because it ______ electrons.

Metals are reducing agents because they lose electrons.

Tap-sort the trend

· 8 of 17Na → Cl across Period 3: metallic character
· 9 of 17Li → K down Group 1: metallic character
· 10 of 17Na → Cl across Period 3: non-metallic character
· 11 of 17F → I down Group 17: non-metallic character
· 12 of 17Increasing metallic character: Li, Na, K
· 13 of 17Decreasing non-metallic character: F, Cl, Br, I
· 14 of 17In Group 14, the non-metal at the top is:
· 15 of 17Period 3 metalloid:
· 16 of 17Non-metals act as:
· 17 of 17Hydrogen is a:
08

Concept check — answer without looking back

1. What is metallic character?
The tendency to lose valence electrons and form a positive ion.
2. What is non-metallic character?
The tendency to gain electrons and form a negative ion.
3–4. What type of ion do metals and non-metals form?
A metal forms a positive ion (cation); a non-metal forms a negative ion (anion).
5–8. State all four periodic trends.
Across a period, metallic character decreases and non-metallic character increases. Down a group, metallic character increases and non-metallic character decreases.
9. Why is sodium more metallic than chlorine?
Sodium is larger and loses electrons more easily; chlorine holds electrons more strongly and tends to gain one.
10. Why is fluorine more non-metallic than chlorine?
Fluorine is smaller and attracts an incoming electron more strongly.

Important “give reason” answers

Why does metallic character decrease across a period?
Across a period, nuclear charge increases and atomic size decreases. Valence electrons are held more strongly and cannot be removed easily. Hence metallic character decreases.
Why does metallic character increase down a group?
New electron shells are added and atomic size increases. The outermost electrons are farther from the nucleus and are removed more easily. Hence metallic character increases.
Why does non-metallic character increase across a period?
Across a period, nuclear charge increases and atomic size decreases. The attraction for incoming electrons increases. Hence non-metallic character increases.
Why does non-metallic character decrease down a group?
Down a group, atomic size increases because new shells are added. The attraction of the nucleus for incoming electrons decreases. Hence non-metallic character decreases.
Why is sodium more metallic than magnesium?
Sodium and magnesium are in the same period, but sodium has a larger atomic size and lower nuclear charge. Its valence electron is removed more easily.
Why is chlorine more non-metallic than sulphur?
Chlorine lies to the right of sulphur in the same period. It has a smaller size and greater nuclear charge, so it gains an electron more easily.
09

Mistakes that cost marks

Tap a statement to see the correction.

Metallic character means the tendency to lose valence electrons and form a positive ion.
A metal characteristically loses valence electrons and forms a positive ion.
Additional shells make the atoms larger, so the nucleus attracts an incoming electron less strongly; non-metallic character decreases.
They are opposite: metallic character decreases, while non-metallic character increases.
Silicon is a metalloid: it has intermediate properties.
Hydrogen is a non-metal. Its placement reflects its one valence electron and ability to form H⁺.
10

Practice questions and answers

Level 1 — easy

  1. Define metallic character.
    Answer
    The tendency of an atom to lose one or more valence electrons and form a positive ion.
  2. Define non-metallic character.
    Answer
    The tendency of an atom to gain electrons, complete its outermost shell and form a negative ion.
  3. What type of ion is formed by a metal?
    Answer
    A positive ion or cation.
  4. What type of ion is formed by a non-metal?
    Answer
    A negative ion or anion.
  5. State the trend in metallic character across a period.
    Answer
    It decreases.
  6. State the trend in non-metallic character down a group.
    Answer
    It decreases.
  7. Name the metalloid in Period 3.
    Answer
    Silicon.
  8. Is hydrogen a metal or non-metal?
    Answer
    Hydrogen is a non-metal.

Level 2 — understanding

  1. Why does a large atomic size favour metallic character?
    Answer
    The valence electrons are farther from the nucleus and are held less strongly, so they are lost more easily.
  2. Why does a small atomic size favour non-metallic character?
    Answer
    An incoming electron is closer to the nucleus and is attracted more strongly.
  3. Why does metallic character decrease across a period?
    Answer
    Nuclear charge increases and atomic size decreases; valence electrons are held more strongly and cannot be removed easily.
  4. Why does non-metallic character decrease down a group?
    Answer
    New shells increase size, reducing the attraction of the nucleus for an incoming electron.
  5. Explain why potassium is more metallic than lithium.
    Answer
    Potassium is lower in Group 1, has more shells and a larger size, and loses its valence electron more easily.
  6. Explain why fluorine is more non-metallic than iodine.
    Answer
    Fluorine is higher in Group 17, smaller, and attracts an incoming electron more strongly.
  7. Why do metals act as reducing agents?
    Answer
    They lose electrons.
  8. Why do non-metals act as oxidising agents?
    Answer
    They gain electrons.

Level 3 — arrange in order

  1. Li, Na, K in increasing metallic character.
    Answer
    Li < Na < K
  2. Na, Mg, Al, Si in increasing metallic character.
    Answer
    Si < Al < Mg < Na
  3. C, Si, Ge, Sn, Pb in increasing metallic character.
    Answer
    C < Si < Ge < Sn < Pb
  4. Cl, S, P, Si in increasing metallic character.
    Answer
    Cl < S < P < Si
  5. F, Cl, Br, I in decreasing non-metallic character.
    Answer
    F > Cl > Br > I
  6. C, Si, Ge, Sn in decreasing non-metallic character.
    Answer
    C > Si > Ge > Sn
  7. Na, Mg, Al, Si, P, S, Cl in decreasing non-metallic character.
    Answer
    Cl > S > P > Si > Al > Mg > Na
  8. N, O, F in decreasing non-metallic character.
    Answer
    F > O > N
11

ICSE-style questions

1. State how metallic character varies across a period and down a group. Give reasons.
Across a period, metallic character decreases because nuclear charge increases and atomic size decreases, so valence electrons are held more strongly. Down a group, it increases because new shells increase atomic size and the outermost electron is removed more easily.
2. State how non-metallic character varies across a period and down a group. Give reasons.
Across a period, non-metallic character increases because increasing nuclear charge and decreasing size increase attraction for incoming electrons. Down a group, it decreases because extra shells increase size and weaken this attraction.
3. Arrange Na, Mg, Al, Si, P in decreasing metallic character.
Na > Mg > Al > Si > P
4. Arrange C, Si, Ge, Sn, Pb in increasing non-metallic character.
Pb < Sn < Ge < Si < C
5. Give reasons: Na is more metallic than Cl; K than Na; F more non-metallic than Br; C non-metal but Pb metal.
Na is larger and loses electrons more easily than Cl, which holds electrons strongly and gains one. K lies below Na, so its valence electron is farther from the nucleus. F lies above Br and is smaller, so it attracts an incoming electron more strongly. Down Group 14, non-metallic character decreases and metallic character increases; thus carbon is a non-metal while lead is a metal.
12

One-minute revision

METALLIC CHARACTER lose electrons → positive ion → reducing agent larger atomic size favours it across a period: decreases down a group: increases NON-METALLIC CHARACTER gain electrons → negative ion → oxidising agent smaller atomic size favours it across a period: increases down a group: decreases MEMORY SENTENCE: Across, metal fades; down, metal grows.

Next lesson

Lesson 6: Chemical reactivity, melting points, boiling points and density trends.