8 mistakes learners make with bonding, each one named and explained.
Conducting needs charged particles that are free to move, whatever the substance is made of.
Metals are said to conduct because they are shiny or hard.
The properties of metals are learned as one list, so any of them can stand in for any other.
Question. Why metals conduct electricity
A common answer. because they are shiny
The answer. because they have delocalised electrons free to move
Why. Being shiny is a separate consequence of the same structure, not a cause of conduction.
An explanation has to name the structure, not another property.
Diamond is described as a metal, or a metal as a non-metal.
Shiny, hard and conducting are all associated with metals, and some non-metals share them.
Question. Diamond and graphite
A common answer. diamond is a metal
The answer. both are forms of carbon, a non-metal
Why. Carbon sits on the non-metal side of the table whatever form it takes.
One shared property does not make something a metal. Check the table, not the appearance.
A substance that conducts only when molten or dissolved is identified as simple molecular or giant covalent.
The clue in the question is about states, and the structures were learned as static diagrams.
Question. Conducts when molten or dissolved, not when solid
A common answer. a simple molecular substance
The answer. an ionic compound
Why. The ions are locked in place in the solid and free once it melts or dissolves.
The pattern of when it conducts is the fingerprint of the structure.
Graphite or a metal is explained as conducting because it contains ions.
Ionic conduction is met first and becomes the only mechanism available.
Question. Why graphite conducts
A common answer. it contains ions
The answer. each carbon bonds to only three others, leaving delocalised electrons free to move
Why. Graphite is pure carbon; there are no ions in it at all.
Either charge carrier works. The question is only whether something charged is free to move.
A covalent bond is defined as electrons being given away rather than shared.
Transfer is the mechanism learned first, in ionic bonding, and it becomes the default.
Question. What a covalent bond is
A common answer. electrons are transferred
The answer. a shared pair of electrons between two atoms
Why. Neither non-metal will give an electron up, so sharing is the only way both fill a shell.
Co means together. The word carries the whole definition.
Magnesium oxide is said to melt higher than sodium chloride because it is heavier.
Heavier feels like it should be harder to pull apart.
Question. Why MgO melts higher than NaCl
A common answer. magnesium is heavier
The answer. MgO has 2+ and 2- ions, so the electrostatic attraction is much stronger
Why. The strength of the attraction depends on the charges, not the masses.
For ionic melting points, always look at the charges first.
Sodium chloride is given covalent, metallic or hydrogen bonding.
Four bonding types are learned together and none of them can be seen.
Question. What holds solid sodium chloride together
A common answer. covalent bonding
The answer. ionic bonding
Why. A metal with a non-metal transfers electrons, which makes ions.
Look at which side of the table each element comes from. That decides it every time.
Graphite is said to have weaker covalent bonds than diamond.
Graphite really is softer, so something about it must be weaker.
Question. Why graphite is soft
A common answer. its covalent bonds are weaker
The answer. the layers are held together only by weak forces between them
Why. The covalent bonds within a layer are as strong as those in diamond.
Softness and melting point often come from the weak forces, not from the bonds themselves.
WAJD spots these patterns in your child's answers and names the one behind their wrong answers, instead of just marking them wrong.