Lesson 5 – The Empirical Formula

The Empirical Formula is the simplest whole-number ratio of atoms of each element present in a compound. It becomes easy when you remember this simple saying: Mass to Moles Divide By Small Multiply till whole An example of this would be: Continue reading →

Lesson 4 – Amount of Substance and the mole

A mole is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope. This number is known as the Avogadro Constant. You can find the mass of one mole of atoms of any element – it is the relative atomic mass in grams. One mole … Continue reading →

Lesson 3 – Atomic Masses

The mass of atoms can not be measured directly; the number would just be too small. So instead the masses are compared using a relative mass. Carbon-12 has been chosen as this reference isotope. You can find the masses of elements on the periodic table. So if I wanted to find out the relative mass … Continue reading →

Gilbert Newton Lewis

Born: October 25, 1875 in Weymouth, Massachusetts. He recieved a PhD from Harvard University in 1899. After this he taught at Harvard and the Massachusetts Insitiute of Technology before he became the dean of the College of Chemistry at the University of California, Berkeley. Lewis is notable for his idea of the “cubic atom”. With this he … Continue reading →

Key Definitions

Relative Atomic Mass – The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of Carbon-12 Relative Isotopic Mass – The mass of an atom of an isotope compared with one-twelfth of an atom of Carbon-12 Relative Molecular Mass – The weighted mean mass of a … Continue reading →

Why is Carbon-12 used as the reference isotope?

Once upon a time, way back before 1961, there actually were two sets of atomic masses (though everybody called them atomic weights then). One scale was used by physicists; the other by chemists.  Both were based on weights compared to Oxygen, rather than Hydrogen.  Oxygen was used because it combines with a lot of things … Continue reading →

Lesson 2 – Atomic Structure

An atom is made up of a nucleus of Protons and Neutrons while Electrons orbit the nucleus in shells. The nucleus makes up the vast majority of the atom’s mass. This is what an atom of Carbon 12 would look like. I say ‘Carbon 12’ because Carbon, aswell as other elements, has different isotopes. Isotopes … Continue reading →

Lesson 1 – The Changing Atom

The idea of the atom was first developed in ancient Greece by a man named Democritus. The word atom comes from the greek word ‘atomos’ meaning indivisible. He thought everything was made out of particles that you could only divide a certain number of times.  We then come to John Dalton who in the early … Continue reading →

Welcome

Hello, welcome to my chemistry blog. After evey chemistry lesson this year I will be blogging about what we have learnt, enjoy! Continue reading →