grade 9 revision ( unit one )

It is the breaking up of bonds in molecules of the reactants and formation of new bonds in the molecules of resultants (products) from the reaction.

• Chemical reaction rate

• Chemical compound

• Chemical reaction

It is the arrangement of metals in a descending order according to the degree of their chemical activity.

• Chemical reaction

• Chemical activity series

• Chemical reaction rate

They are chemical reactions in which double substitution (exchange) occurs between the ions (radicals) of two different compounds to give two other new compounds.

• Double substitution reactions

• single substitution reactions

• substitution reactions

A chemical process which causes the decrease in the oxygen percentage or the increase in the hydrogen percentage in a substance.

• painting process

• reduction process

• Oxidation process

It is the substance which gives oxygen or takes hydrogen away during a chemical reaction.

• Oxidizing processes

• Oxidizing agent (factor)

• reducing agent (factor)

It is the change in the concentration of the reactants and the resultants in a unit time.

• The speed of physical change

• The chemical reaction

• The speed of chemical reaction

They are chemical reactions in which the catalyst increases their speeds.

• Positive catalytic reactions

• negative catalytic reactions

• Positive reactions

They are chemical substances produced by the body of living organism act as catalysts that increase the speed of biological reactions.

• hormones

• Enzymes

• lipids

They change (increase or decrease) the speed of chemical reactions.

• hormones'

• enzymes

• Catalysts

It increases the speed of decomposition of hydrogen peroxide.

• Oxidase

• Oxidase enzyme

• Oxidase hormon