Atoms They make up EVERYTHING!!!

This information is REALLY Important for the Rest of your Educational Career!!!!

Elements An element is a pure substance that cannot be broken down into anything simpler by chemical or physical means –Elements are the “purest” pure substance –Oxygen, gold, and carbon are all elements –Elements each have distinct chemical and physical properties!!

What is an atom? Atoms are the smallest particle of an element that still has the properties of that element. All of the atoms of an element are exactly alike!!!

What do atoms look like? If you could see an atom, it would look like a tiny ball. –Everything in the universe is made up of these tiny little spheres.

What is inside atoms? Atoms are made up of two parts: –The electron cloud – the part around the outside that you see The nucleus – the really tiny part in the middle

The nucleus is made up of 2 main particles… Protons Neutrons Electrons And in the electron cloud are the small but still important… Nucleus

Protons Found in the nucleus Positively charged Determines atomic number Mass = 1 AMU

Neutrons Found in the nucleus Neutrally charged Most massive particle (1.011 AMU) Helps determine atomic mass

Electrons Negatively charged Fly around the nucleus in a “cloud” Determine how much an atom will bond with other atoms Tiny! Mass < AMU

And when all these parts come together, they form… An Atom… With a nucleus… And its electron cloud

The electrons in the cloud move so fast that they seem to be a solid shell

SPACE! The distance between the nucleus and the electron clouds is HUGE!!! Like a pea in a football stadium is the nucleus and the farthest seats are the electrons! But almost all of the atom’s mass is in the “pea”

Atomic Number The atomic number is equal to the number of protons in an atom This tells you what element it is! Ex. Hydrogen has 1 proton, so its atomic number is 1. –If an atom has 1 proton, it must be hydrogen! Helium has 2 protons, so its atomic number is 2.

More atomic numbers (Use the periodic table on page 328) If an atom has 22 protons, what is it? Titanium What is the atomic number for oxygen? 8 How many protons does iodine have? 53 C Atomic number

Atomic Mass Number Atomic mass number = the number of protons plus neutrons in the nucleus of ONE ATOM. (we don't count electrons, they are too small!) Ex. The nucleus of a carbon atom has 6 protons and 6 neutrons… …so its atomic mass number = 12

…more mass numbers An atom of chlorine has 17 protons and 18 neutrons, what is its atomic mass number? 35 An atom of copper has 29 protons and an atomic mass number of 63, how many neutrons does it have? 34 An atom of calcium has 20 protons, and an atomic mass number of 40, how many neutrons does it have? 20

Isotopes The number of neutrons that atoms have can vary. Some carbon atoms have 6 neutrons, some have 8! Atoms with the same number of protons, but different numbers of neutrons are called isotopes. 6 protons 6 neutrons Mass=12 C12 6 protons 8 neutrons Mass=14 C14

This is a little tricky… Atomic mass is NOT the same as atomic mass number. Atomic Mass number = protons + neutrons for 1 atom Atomic Mass = AVERAGE of protons plus neutrons for ALL ISOTOPES of an element.

That’s why masses on the periodic table are decimals!! C Atomic mass There are billions of carbon atoms in one piece of pencil lead, the atomic mass is the average of the mass numbers for all of these atoms!