Poem on Chemistry

Poem on chemistry
A wonderful subject, chemistry
engaging than a book of mystery
With atom, molecule, mass and mole
Observing matter as a whole
Being a branch that studies
The composition, interaction and properties
we observe in matter
and know how chemical transformations occur
We know matter exists as solids, liquids
and a multitude more as gases
Changing in state with temperature and pressure
exhibiting their properties as their character
Also classified as elements and compounds
and often found in form of mixtures.
Elements,the purest of them all
with only one type of atom at all
when they combine in fixed ratio
compounds come to show
If not, here comes the mixtures
I don't know what rhymes with it here
When the properties of a substance are studied,
measurement is inherent
Units and measurement, around the world
Different everywhere in meaning and word
Then the International system of units appeared
uniform and common around the world
The range of measurements, not one, nor three
spread wide from ten power minus thirty one- ten power twenty three
So now in numbers, there's uncertainty
large numbers are now expressed exponentially
to measure and calculate easily
When different values are laid in a row
Precision and accuracy need to be known
Precision refers to closeness, accuracy to agreement
of a particular value, to true value of result
Now significant figures, used commonly
are meaningful digits, known with certainty
This also implies a few rules
All non- zero digits declared significant
Zeroes preceding the former not significant
while converting one unit to another,
no change will occur to significant figures.