Elements, Compounds and Mixtures II Flashcards
Periodic table of elements
A table that organises elements according to their properties
Two main groups of elements
- metals
- non-metals
Separated by the zig-zag line on the periodic table
Group
Elements in the same vertical column
Elements in the same groups have similar chemical properties
The first true periodic table
By Dmitri Ivanov Mendeleev in the nineteenth century
Chemical symbols
Represent elements
Example: carbon = C
Period
Elements in the same horizontal row
Compound
A substance made up of two or more elements chemically combined
Characteristics of compounds
-usually compounds’ properties are different to its constituents
(Sodium chloride is edible, while sodium/chlorine are poisonous)
-compounds’ constituents are always combined in a fixed proportion by mass
Formation of compounds
- formed by chemical reactions
- combustion (chemical combines with oxygen in the air)
- when elements/compounds come in contact/touch each other
- decomposition (when a compound is heated to form simpler compounds)
Separation of compounds
- passing electricity through it
- heating compounds
- exposure to light
Mixture
Consists of two or more substances mixed (NOT chemically combined)
Properties of mixtures
- no chemical reaction when combined
- has the same properties of its constituents
- mixtures can be separated easily with physical methods (not chemical)
- not mixed in a fixed proportion
Different types of mixtures
- solid-liquid (certain drinks (chendol))
- solid-solid (concrete)
- liquid-liquid (alcoholic beverages)
- liquid-gas (soft drinks)
- gas-gas (the air)
