what does this mean?

Question

what does this mean?
" recognize compounds as pure substances which may be broken down into elements by chemical means"

Answer 1

Compounds (for example, water, H2O) are pure substances. Water is only water, and not a mixture of other substances (like, say, lemonade, which is a mixture of the compounds water, sugar, and lemon juice). However, although this compound (water) is a pure substance, it is made up of atoms, which are elements. In waters case, two hydrogen atoms and one oxygen atom. Through chemical reactions, the bonds between the oxygen and hydrogen atoms can be broken and the elements seperated. However, then you would no longer have water.

To put it another way, elements are the building blocks of all matter, and compounds are made of elements. However, compounds, if broken down into their constituent elements, are no longer compounds.

Answer 2

Compounds are made of two or more elements and can be broken down into the elements through suitable chemical reactions. Chemical compounds may or may not be pure but the statement applies to pure substances. If impure, the impurities may affect the chemical reactions and even may contaminate the reaction products.

Answer 3

- Recognise compounds - H2O(l) = water which is a pure substance
- Broken down into elements - O2(g) = oxygen & H2(g) = hydrogen
- By chemical means - H2O(l) can undergo electrolysis(redox reaction) to form it's constituent elements.

You just need to know that compounds can be broken down by different chemical methods to form the base elements it is made from.

Answer 4

I like Tim's answer, go with his