matter and mass:

Matter can be defined as the amount of a substance to exist or any object which has a mass and occupies space

• Density is the measurement of how tightly a material is packed together

• The density is inversely proportionate to the volume

  

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The law of conservation of mass states that mass in an isolated system can neither be created nor destroyed. Energy can only be transferred into different forms and the total mass of the reactants in a chemical reaction would equal the sum of the mass of the products.

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classification of matter:

• Atoms: smallest part of any element while still retaining the properties of that element. Made up of protons, neutrons and electrons (3 subatomic particles), For example: Hydrogen atom, Oxygen atom
• Element: Substance made up of only one type of atom. For example: Hydrogen, Oxygen
• Compound: Composed of two or more different atoms that are chemically bonded and cannot be separated through physical means. Atoms are also in a fixed ratio, for example: H2O2 or H2O
• Mixture: Composed of two or more different atoms that are not chemically bonded and can be separated by physical means, for example salt water can be separated to salt and water
• Molecule: Two atoms (can be same or different) that are chemically bonded. This can be a molecular element or molecular compound.

• A pure substance is an element or compound which would contain only one substance with noother substances acting as an impurity or it can be defined as a substance which has a uniform atomic structure where all the molecules are uniform and have the same build. It has a clear melting point and is always homogeneous.
• An impure substance or mixture would have many different elements or compounds mixed together where there can be a mix of different molecules made up for different atoms. It does not have a clear/definite melting point, and is usually a mixture and always heterogenous.

states of matter:

• Solids:

  • Regular arrangement, particles are packed closely together.
  • Vibrate in fixed positions, no movement.
  • Strong forces of attraction between particles.
  • Least kinetic energy.

  

• Liquids:

  • Particles are touching but have gaps between them.
  • Irregular arrangement.
  • Can move around each other.
  • Weaker forces of attraction.
  • More kinetic energy than solids.

  

• Gases:

  • Particles are far apart and move randomly at high speeds.
  • No forces of attraction between particles.
  • Highest kinetic energy.

  

Phase Change:

• When a substance changes from solid to liquid there will be a gain in kinetic energy because there is more space for the particles to move around and the same applies for liquid to gas.
• While when an object moves from gas to liquid and liquid to solid there is a decrease in the amount of kinetic energy

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During melting or boiling, energy is used to break forces between particles instead of increasing temperature.

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