electrons orbit around the nucleus in orbits with a set size and energy

realised atoms are divisible and contain electrons

Plum pudding model (electron are like the chocolate chips on a cookie, and cookie is the positive mass)

discovered positive nucleus with electrons orbiting it in empty space

"matter can't be continuously cut forever- the smallest thing in the universe is called an atom (unbreakable)"

There are different types of atoms (elements)

Most traveled straight through, but a few were deflected

smallest thing in the universe that is unique to each other

2 (+) types of atom joined together chemically

2 or more substances that aren't chemically joined together

atoms of the same element with a different number of neutrons

A charged atom due to an imbalance of electrons and protons

The chemical properties of an element depend on how many electrons

The way an element reacts depends on the number of electrons in its outermost shell

The first energy level (nearest the nucleus) can hold up to 2 electrons

The second energy level can hold up to 8 electrons

The third energy level can hold up to 8 electrons

The number of protons = atomic number

The number of protons + neutrons = mass number

-

-

e.g. to separate sand and salt, add water to the mixture and filter in through filter paper. The dissolved salt is in the flask, and sand in the paper. Dry the sand in an oven to evaporate water and leave pure sand.