Elements, Compounds and Mixtures
Subdecks (2)
Cards (24)
- what is an element?an element is a pure substance which cannot be split into simpler substances by any chemical process.
- There are 103 elements
- An element may consist of individual atoms of the same kind, e.g. copper Cu2, or molecules composed of atoms of the same kind, e.g. oxygen O2
- MetalsLithium LiSodium NaPotassium KUranium ULead PbTin SnAluminium AlBeryllium BeMagnesium MgCalcium CaBarium Ba
- Compounds are...a substance containing two or more different types of element bonded together chemically in fixed proportions and in such a way that their properties are changed.
- magnesium (element) + oxygen (element) = magnesium oxide (compound)
- compounds may be represented by chemical formulae.
- Mixtures...a mixture consists of two or more substances combined together physically.
- Mixtures can be classified as:
- solution
- suspension
- colloid
- Heterogeneous mixtures...a heterogeneous mixture is a non-uniform mixture. e.g. suspensions and colloids.
- Homogeneous mixture is...a uniform mixture; it has the same composition and properties throughout the mixture. e.g. solutions
- solutionthis is formed when the solute is completely dissolved in the solvent e.g. sugar and water.
- soluteis the substance to be dissolved
- solventis the substance doing the dissolving.
- water is an excellent solvent
- suspension is...a heterogeneous mixture that contains solid particles that do not dissolve. e.g. sand and water
- colloids...colloid is a a homogeneous mixture. e.g. milk and water
- pure substancea pure substance consist of only one type of material
- Pure substances have fixed melting and boiling points
- Impurities lower the melting point and raise the boiling point of a pure substance
- How do you find out if a substance is pure?Its melting or boiling point is determined