Short Course on Chemical Equations

Science and Math on the GED 2014

Can you guess what elements you are made of? You might guess that we are made of 30 or 40 different types of elements. In actuality, humans are made up of just a few common elements. In fact, 99% of our bodies are made by only 6 common elements and the top three are; oxygen being the most common at 65%, followed by carbon at 18% and hydrogen at 10%.

However, breaking down the human body in terms of elemental make-up does not do us justice. As Hermann Muller put it, "To say that a man is made up of certain chemical elements is a satisfactory description only for those who intend to use him as a fertilizer."

Some Common Elements You Should Recognize

Hydrogen or H H is the most abundant element in

the Universe, making up 75% of its mass.

Oxygen (or O) is the fuel our cells need to live.

Lithium or Li

Magnesium or Mg

Carbon or C

Fluorine (F)

Iron (Fe)

Sodium (Na) Sodium Chloride (NaCl)

Chemistry and Math Balance

We have been learning what balance means in math. This also applies to science.

2 + 4 =6 Both sides are balanced (they both equal 6)

In Chemistry we also balance: Mg + O2→ MgO when balanced

becomes 2 Mg + O2 → 2 MgO Note: The arrow is like an equal sign.

Mg + O2→ MgO becomes 2 Mg + O2 → 2 MgO

Notice in the original there is 1 Magnesium (Mg) on each side of the equation. On the left side there are 2 Oxygens (O). The subscript 2 means there are 2 of them. On the right side of the equation there is a 1 Mg and 1 O. They are not balanced.

When I balanced them, I put a 2 in front of the Mg so now there are 2 Mg and 2 O on the left side. I also put a 2 on the right side in front of the MgO. This 2 means there are 2 Mg and 2 O. (It essentially distributes to each element)

Another example is H2O→H2 + O2 When balanced it becomes 2 H2O→ 2H2 + O2

There are now 4 H and 2 O on each side of the arrow.

Atoms: The smallest unit of matter

An atom is made up of 3 main parts Proton-has a positive charge Neutron- which has no charge Electron-has a negative charge This website shows a visual of an

atom.

on the periodic table, the number above the element symbol (the atomic number) indicates the number of protons an element has. For example, the atomic number of C, carbon, is 6.

This is also the number of electrons in a neutral atom.   To find the number of neutrons round the number below the

chemical symbol (atomic mass) to the nearest whole number. Subtract the atomic number from this number. This is the number of neutrons.

Example: C- atomic number is 6 = # protons Atomic weight is 12.01 rounded to 12 # of neutrons = 12-6 =6 # of electrons=6 = # of protons