Chemistry Foundations Understanding matter & chemical reactions.
Atom
Element
Molecule
Compound
Atoms are the smallest part of an element. It is to small to be seen with the human eyes
Democritus was a greek philosopher who realised that everything is made up of tiny particles. He called these particles atoms from the greek word atomos meaning inadvisable
Elements are made up of atoms which are not chemically bonded together as they are the same atom
There are about 100 different elements. They are put onto the periodic table
A compound has 2 or more atoms chemically bonded together. These can be the same element or different kinds. EG h2o or h2.Some compounds can be called molecules if they have 2 or more different kinds of atoms
Molecules has two or more atoms form chemical bonds. How ever they can never be just one singular atom always two or more different ones.eg C6H12O6 the make up for glucose.
Subatomic particles
Atoms are made up of three parts. Protons, neurtons and electrons. The protons and neurtons make up the nucleus
Proton: 1 mass,Postive charge, location in the nucleus.
Neutrons:Mass 1, No charge/neutral, location in the nucleus
Electrons:0 mass,negative charge and located in the electron shell.
Understanding elements structure.
the bigger number on the periodic table is the mass number. The smaller number is the atomic number. from this we can work out how many electrons, protons and neutrons there are in each element.
for example magnesium has the atmoical number of 12 and the mass number of 24.
The atomic number is how many protons and electrons there are, so all we need to work out is the number of neurons it has to do this use the following eqaution
mass 12=protons 24 + neutrons
neurtons= 12(mass)-24 (protons)
neurtons=12
Bonding
Ionic bonding. One was ordinary atoms to look like noble gases on the outside is to transfer electrons completely and become ions.
Elements will transfer spare electrons to other elements that need electrons to stable themselves and the other elements
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structural formula 
word formula. Hydrogen + Oxygen -> Water
symbol formula. 2H2+02->2H20
covalent bonding. When atoms are too similar, transferring of electrons is not possible. But atoms can still try look like noble gases on the outside by forming molecules with sharing electron pairs.