What is an element?
- a substance that cannot be broken down into other substances
- There are 109 elements
What is an atom?
Smallest particle of an element
What is a molecule?
- The smallest particle of substance that can exist by itself and has all the properties of that substance.
- Oxygen, hydrogen, nitrogen and chlorine molecules are made of 2 atoms each.
What is a compound?
- Made up of 2 or more elements that have been chemically combined.
- The elements lose their individual identities when they are joined. The compound has new different properties.
What is a mixture?
A combination of 2 or more substances that keep their own properties.
What are the common compounds?
acids, bases, salts and oxides
- contains hydrogen ions (H+)
- usually has a sour taste
examples of acids
vinegar and lemon juice
- sulfuric acid (H2SO4)
- nitric acid (HNO3)
- carbonic acid (H2CO3)
- acetic acid (HC2H3O2)
- used in medicines, alcohol, dyes, and car batteries
- used in fertilizers, explosives, and cleaning materials
- used in making plastics, rubber, photographic film, and as a solvent
- contain hydroxyl ions (OH-)
- bitter taste and stronger ones feel slipper
example of Bases
household cleaning products
- sodium hydroxide (NaOH)
- ammonium hydroxide (NH4OH)
- potassium hydroxide (KOH)
- calcium hydroxide (Ca (OH)2)
- used in making soap, paper, vegetable oils and refining petroleum
- making deodorants, bleaching compounds and cleaning compounds
- making soaps, drugs, dyes, alkaline batteries and purifying industrial gasses
- making cement and plaster
What is an indicator
a substance that changes color when it comes into contact with a base or acid
- blue litmus paper turns red in an acid
- red litmus paper turns blue in a base
How is salt formed?
When an acid and a base combine chemically.
- formed when oxygen combines with another element
- ex: rust forms when oxygen combines with iron
- 1 or more substances are formed
- energy is released during reaction
when the quantities of reactants and products are at a steady state