Introduction: Matter & Measurement

Question 1

Elements

Answer 1

Substances that cannot be decomposed into simpler substances. On the molecular level, each element is composed of only one kind of atom

Question 2

Compounds

Answer 2

Compounds are substances composed of two or more elements; they contain two or more kinds of atoms. Water, for example, is a compound composed of two elements: hydrogen and oxygen.

Question 3

Mixture

Answer 3

Mixtures are combinations of two or more substances in which each substance retains its chemical identity.

Question 4

Classification of Matter

Answer 4

Question 5

Significant figures rules

Answer 5

Zeros between nonzero digits are always significant—1005 kg (four significant figures); 7.03 cm (three significant figures).

Zeros at the beginning of a number are never significant; they merely indicate the position of the decimal point—0.02 g (one significant figure); 0.0026 cm (two sig- nificant figures).

3. Zeros at the end of a number are significant if the number contains a decimal point—0.0200 g (three significant figures); 3.0 cm (two significant figures).