Multiple states of matter - mixture
Same state of matter - pure
Separated physically- mixture
Consistent properties - pure
Can’t be separated- pure
Can’t be a single element - mixture
Answer is: elements in the same group have similar chemical properties.
Periodic law<span> is the arrangement of the </span>elements<span> in order of increasing atomic number.
</span>For example all alkaline metals (I group of periodic table, Na, K, Cs...) loose one electron in chemical reaction and react vigorously with water.
Group 2 because the outer electrons ( also known as valence electrons) are 2 and that’s how we know which group it is in
The terms and their definitions are as follows:
1. Energy
B. The capacity to do work.
Energy comes in different forms, each relating to a different type of work. For example, kinetic energy and potential energy.
2. Volatile
D. Substance that changes to gas easily at room temperature
Volatile substances do not have strong attractive forces between their molecules, so they are easily overcome at room temperature and the substance evaporate. For example, petrol.
3. Chemical Reaction
H. Another term for chemical change
4. Chemical Change
G. <span>The change of one or more substances into other substances
</span>Chemical changes involve rearrangement or removal of atoms from a substance
5. Endothermic
J. Any chemical reaction that absorbs energy
These reactions require the addition of heat energy to take place
6. Exothermic
F. Any chemical reaction that gives off energy
Exothermic reactions are associated with a rise in temperature of the system
7. Density
I. The amount of matter contained in a unit volume
Density is characteristic of a substance and independent of the amount that is present
8. Physical property
A. Can be observed without any change in the identity of the substance
Physical changes include breaking and state changes
9. Law of conservation of mass
E<span>.The fact that matter can be neither created nor destroyed in a chemical change.
This is true for any reaction in the universe
10. Chemical property
</span><span>C. Can be observed only when there is a change in composition of a substance
11. Physical Change
K. </span>The type of change in which the identity of substances does not change
