4.) an element cannot be decomposed by a chemical change, it is a pure substance and no other materials compose it.
It is important to use chemicals of high quality and correct concentrations in experiment so that we can obtain the predictable result in an experiment
Purity of substances/chemicals is very important when performing experiments in the laboratories, because it plays an important role in the determination of the chemical properties of substances which will have a direct effect on the result obtained from the experiment. likewise using the correct concentration of reagents
During experiments to obtain the best/predictable result in an experiment it is of best practice to make use of chemicals of high quality and also at the exact(needed) concentrations, that way the predictable result of the experiment will be obtained.
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Elements are ordered from left to right, increasing atomic number as they go. The periodic table allows us to find out and predict things about elements that haven’t been discovered yet!