Atomic Structure Objective: Describe the general structure of the atom, and explain how the properties of the first 20 elements in the Periodic Table are related to their atomic structures

Brainstorm What is matter? What is mass? What is an atom? Give at least three examples. Give two examples of things that are NOT matter, (Hint: thoughts). What is mass? What is an atom? Give at least three examples of things in this room that are made of atoms. Is the air we breathe made of atoms? Explain your answer. What is a scientific theory?

The Basics Matter: Anything that takes up space and has a mass. Examples: a desk, a person, oxygen Non Examples: feelings, thoughts Mass: A measure of how much matter an object contains. Mass is related to weight. Element: A substance that can not be broken down into a more simple substance. Example: Gold, Oxygen, Carbon, Helium, Iron

The Basics Compound: A substance made of two or more elements. Example: CO2 , H2O Theory: A tested explanation with supporting evidence. Can be changed, revised or disproved. Example: Theory of Evolution-The change in physical traits in a population over long periods of time.

Discussion Can scientist be proven wrong? Can science theories be changed? Is science a process that is continually worked on or is it set in stone? Do many people usually contribute science knowledge?

Activity

Discovering the Atom Aristotle: Greek Philosopher 322 BC-384BC Believed that four elements made up all things

Discovering the Atom: Dalton’s Contribution John Dalton England 1776 Science Teacher Atom looked like a ball Theory: All matter is made up of individual particles called atoms, which cannot be divided.

Discovering the Atom: J.J. Thomas 1800 Discovered the electron Plum pudding model

Discovering the Atom: Ernest Rutherford 1900 New Zealand Discovered protons and nucleus Electrons move randomly in space

Discovering the Atom: Niels Bohr 1913 Electrons move in fixed orbit around nucleus

Discovering the Atom: Schrodinger and Chadwick Erwin Schrodinger: 1926 Describes motions of electrons Leads to electron cloud theory James Chadwick 1932 Confirms the existence of neutrons Nucleus contains neutrons and protons

The Atom – “Uncut” or “Indivisible” The smallest part or unit of an element. Cannot be broken down without losing its properties Basic building block of matter Makes up all physical things

Parts of the Atom Protons Positively charged sub-atomic particle Found in the nucleus Neutrons Neutrally or no charge Subatomic particle found in the nucleus Electrons Negative charge Subatomic particle found outside of nucleus Nucleus Dense center of the atom Positive charge

Atomic Number The number of protons for any given element All element of one kind have the same number of protons Example: All Hydrogen (H) atoms have just one proton Atoms of different elements have different number of protons Atomic number also gives us the number of electrons

Discuss What charge are protons? What charge are electrons? Why do you think atoms have the same number of protons and electrons?

Neutral Atoms The positive protons and negative neutrons balance out. This make the charge of an atom neutral or zero. Draw an Example

Mass Number The number of protons and neutrons found in the nucleus Protons + Neutrons = Mass Number Example: Carbon has a mass number of 12 This means there are 6 protons and 6 neutrons *Do the math

Practice Calculating the Number of Neutrons

Periodic Table

Bohr Model Looks like the solar system Contains different energy levels General Example:

Energy Levels and Orbitals Each ring of the Bohr Model is an energy level As you go further out from the nucleus the energy of the electron becomes greater Electrons orbit around the nucleus much like the earth orbits around the sun

Electron Configuration Configuration = Arrangement Desks in the classroom are arranged in a specific way Electrons are found in orbits around the nucleus. This is their “electron configuration”

Energy Levels and Orbits Can contain only two electrons Energy levels 2 and 3 Can contain up to eight electrons Energy levels must be filled before electrons can move to the next shell *Draw example labeling energy levels