Additional science revision

Physics P2 revision

https://www.youtube.com/watch?v=Tmi-kvvXx70 (Embed)

Chemistry C2 revision

https://www.youtube.com/watch?v=k0r6wVbFZOs (Embed)

The structure of substances

Ionic compoundsGiant structures of ions.They are held together by strong forces of attraction that act in all directions between oppositely charged ions. this is called ionic bonding.Ionic compounds:have a high melting an boiling pointconduct electricity when molten or in solution as the ions are able to move freely.

Ionic bondsAn ionic bond occurs between a metal and a non metal. It involves a transfer of electrons from one atom to another.This forms electrically charged ions, which all have a completed outer energy level.

Forces and their effects

terminal velocityAn object falling will initially accelerate because of the force due to gravity.Eventually the resultant force will be zero as the weight and resistive forces balance.The object will then travel at a steady speed which is called its terminal velocity.

The structure of substances

Alkali metals and halogensAlkali metals:1 electron in their outer shellreact with non metal elements to form ionic compounds where the metal ion has a single positive charge.Halogens: seven electrons in their outer shell react with alkali metals to form an ionic compound where the ions have a single negative charge.

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The structure of substances

Mixtures and compoundsA mixture is two or more elements of compounds that aren't chemically combined.A compound is a substance where two or more elements are chemically combined.Atoms can form chemical bonds by sharing electrons or gaining or losing electrons.

Simple molecular compoundsSubstances that consist of simple molecular compounds are gases, liquids or solids that have a relatively low melting or boiling point. The molecules have no overall electrical charge, so they cant conduct electricity. They have weak intermolecular forces.