un finished science assessment practice

In chemistry, a compound is a substance made up of two or more different chemical elements combined in a fixed ratio. E.g = Water, carbon dioxide and table salt

A mixture is composed of one or more pure substances in varying composition. E.g = Dirt and water (Mud)

There are two main categories of mixtures: homogeneous mixtures and heterogeneous mixtures.

Matter can exist in three forms or phases: solids, liquids, or gases.

The general properties of matter such as color, density, hardness, are examples of physical properties.

Properties that describe how a substance changes into a completely different substance are called chemical properties.

Metals are generally shiny, malleable, and hard. Metals are also good conductors of electricity

an element or substance that is not a metal. They do not conduct electricity or heat very well

they share characteristics of both metals and non-metals and are also called semimetals.

A physical property is a characteristic of matter that is not associated with a change in its chemical composition. e.g = density, color, hardness, melting and boiling points, and electrical conductivity.

An element is a fundamental item that can't be easily broken into smaller pieces. They only contain 1 type of atom.

A Compound is made up of two or more atoms of different elements joined by chemical bonds. A compound has very different properties from the elements from which it is made.

e.g CO2 = carbon dioxide e.g H20 = water

A Molecule is made up of two or more atoms joined by chemical bonds. The atoms joined together in molecules may be different or the same. Some elements exist as molecules – e.g. N2, O2 or H2

Atoms consist of an extremely small, positively charged nucleus surrounded by a cloud of negatively charged electrons. In the neucleus there is neutrons and protons.

the smallest particle of a chemical element that can exist. everything is made from atoms. there to tiny to see.

Mixtures can be physically separated by using methods that use differences in physical properties to separate the components of the mixture, such as evaporation, distillation, filtration and chromatography.

Physical = paper being folded into a paper aeroplane {folded} Chemical = logs turned into burning logs {combustion}

-change in temperature -change in colour (eg rusting) -bubbles

rusting photosynthesis digestion

Photosynthesis is the chemical process used by plants to produce energy. The plant takes in Carbon dioxide and water, uses the energy of the sunlight, to produce Glucose and Oxygen.

The process by which organisms break down glucose into a form that the cell can use as energy

A substance that has a fixed chemical composition throughout is called a pure substance such as water, air, and nitrogen. A pure substance does not have to be of a single element or compound.

A separation process is a method that converts a mixture or a solution of chemical substances into two or more distinct product mixtures, you can do this by using a separating funnels and evaporation.

Evaporation occurs when energy (heat) forces the bonds that hold water molecules together to break.

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It is the process of filtering something. While preparing tea, a filter or a sieve is used to separate tea leaves from the water.