-Describe the differences between elements, compounds and mixtures
Atom is smallest particle of an element. Molecule is made of two or more atoms chemically combined together.
Element is the simplest substance that cannot be broken down by any chemical methods.
All Elements are listed in the Periodic Table.
Elements can exist as atoms or molecules.
Compound is made of two or more elements chemically combined together.
Compound can exist as molecules or ions. Examples of compounds: water, carbon dioxide, ethanol.
Mixture is made from two or more substances physically combined together.
Examples of mixtures: seawater, air, petroleum
Differences between Element and Compound
| Element |
compound |
| Simplest form of matter |
Consists of two or more different elements chemically combined together |
| Consist of only particles of one elements |
consist of particles of different elements |
| Cannot be decomposed into simpler substance by chemical methods |
Can be decomposed into simpler substance by chemical methods |
Differences between mixture and compound
| Compound |
Mixture |
| Elements are joined chemically in fixed proportions by mass |
Constituents present in variable proportions |
|
Formed by chemical reaction.
Heat change is involved
|
No chemical reaction involved.
Usually no heat change is involved
|
| Have properties different from properties of constituent elements |
Have same properties same as constituents |
| Elements in compounds can be separated by chemical means |
Constituents are separated by physical means |
| Fixed melting and boiling point |
Melts and boils over a range of temperatures |