chapters 1-5 chemistry revision (key notes)

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chapter 1 pages-14-46

elements and compounds

an element is a substance that cannot be broken down.

all elements are listed in the periodic table.

copper is an element. It cannot be broken down into any smaller substances,but salt can. The name for common salt is sodium chloride which is a

compound as it can be broken down to make sodium and chlorine. This cannot be broken down any further.

Atoms

,formulae and equations

elements are made up of atoms that are all the same

compounds are made up of atoms that are not the same.

examples of compounds:

CO 2- carbondioxide

S 8-sulfur

Mixtures

mixtures can be easily separated as they are not chemically joined.

they can be separated by processes such as filtration,distillation,crystallisation and chromatography.

what does an atom look like -

(see pages 22-23 in textbook for labelled diagram)

The periodic table

All the different elements are arranged in a chart called the periodic table. A Russian scientist called Dmitri Mendeleev produced one of the first practical periodic tables in the 19th century. The modern periodic table is based closely on the ideas he used:

the elements are arranged in order of increasing atomic number

the horizontal rows are called periods

the vertical columns are called groups

elements in the same group are similar to each other

comparing non-metals with metals

metals have a higher density as compared to non-metals. Metals look smooth and shiny, while non-metals usually appear dull. ... Conversely, non-metals are insulators, and so they do not support conduction of heat and electricity. Metals have a very high melting and boiling point.

group 0