HISTORY OF THE ATOM 460 BC Democritus develops

HISTORY OF THE ATOM 460 BC Democritus develops the idea of atoms he pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he called ATOMA (greek for indivisible)

HISTORY OF THE ATOM 1808 John Dalton suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them ATOMS

HISTORY OF THE ATOM 1898 Joseph John Thompson found that atoms could sometimes eject a far smaller negative particle which he called an ELECTRON

HISTORY OF THE ATOM 1904 Thompson develops the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron's charge like plums surrounded by pudding. PLUM PUDDING MODEL

HISTORY OF THE ATOM 1910 Ernest Rutherford oversaw Geiger and Marsden carrying out his famous experiment. they fired Helium nuclei at a piece of gold foil which was only a few atoms thick. they found that although most of them passed through. About 1 in 10, 000 hit

HISTORY OF THE ATOM helium nuclei gold foil helium nuclei They found that while most of the helium nuclei passed through the foil, a small number were deflected and, to their surprise, some helium nuclei bounced straight back.

HISTORY OF THE ATOM Rutherford’s new evidence allowed him to propose a more detailed model with a central nucleus. He suggested that the positive charge was all in a central nucleus. With this holding the electrons in place by electrical attraction However, this was not the end of the story.

HISTORY OF THE ATOM 1913 Niels Bohr studied under Rutherford at the Victoria University in Manchester. Bohr refined Rutherford's idea by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons.

Bohr’s Atom electrons in orbits nucleus

HELIUM ATOM Shell proton + - N N + electron What do these particles consist of? - neutron

ATOMIC STRUCTURE Particle Charge Mass proton + ve charge 1 neutron No charge 1 electron -ve charge nil

The Atoms Family was created by Kathleen Crawford, 1994 Presentation developed by Tracy Trimpe, 2006, http: //sciencespot. net/

The Atoms Family Story In the center of Matterville, there is a place called the Nucleus Name: Arcade, where two members of Patty Proton the Atoms Family like to hang Description: out. Perky Patty Proton, like Positive her sisters, is quite large with a Favorite Activity: huge smile and eyes that sparkle Hanging out at the Nucleus (+). Patty is always happy and Arcade has a very positive personality. Nerdy Nelda Neutron is large Name: like Patty, but she has a boring, Nelda Neutron flat mouth and eyes with zero Description: expression (o). Her family is very Neutral apathetic and neutral about Favorite Activity: everything. Patty, Nelda, and Hanging out at the Nucleus their sisters spend all their time at Arcade the arcade.

Around the Nucleus Arcade, you will find a series of roadways that are used by another member of the Atoms Family, Enraged Elliott Electron. Elliott races madly around the Arcade on his bright red chromeplated Harley-Davidson. He rides so fast that no one can be sure where he is at any time. Elliott is much smaller than Patty and Nelda and he is always angry because these bigger relatives will not let him in the Arcade. He has a frown on his face, eyes that are squinted with anger, and a very negative (-) attitude. Name: Elliott Electron Description: Negative Favorite Activity: Racing around the arcade

The first energy street can only hold only two Electron brothers. The second energy street, called the Energy Freeway, can hold 8 brothers. The third energy street, called the Energy Superhighway, can hold 18 of the brothers. Energy Freeway Can hold 8 electrons Energy Street Can hold 2 electrons Energy Superhighway Can hold 8 electrons Nucleus Arcade Contains protons & neutrons

The morale of Matterville is stable as long as each negative Electron brother is balanced out by one positive Proton sister. The number of residents in Matterville depends on the Proton and Neutron families. Challenge: What would happen to the morale of Matterville if one Elliott Electron was kidnapped?

Challenge 2: What would happen to the morale of Matterville if one Elliott Electron moved to Matterville?

Subatomic Particles 1. 2. 3. 4. 5. 6. 7. 8. What are the subatomic particles of an atom? Where are the protons located in the atom? What electrical charge do protons have? Where are the neutrons located? What electrical charge do the neutrons have? Where are the electrons located in an atom? What electrical charge do electrons have? How does the number of protons affect the properties of an atom?

Models of Atoms Dish # Protons Neutrons Electrons Atomic Elem ent (+) (0) (-) # Atom ic mass

ATOMIC STRUCTURE He 2 4 Atomic number the number of protons in an atom Atomic mass the number of protons and neutrons in an atom number of electrons = number of protons

The Atoms Family - Atomic Math Challenge Atomic Number Symbol Name Atomic Mass electrons protons Atomic number equals the number of _____or________. neutrons protons + ________. Atomic mass equals the number of ______

30 8 16 65 8 30 8 8 3 7 3 35 4 30 3

5 35 28 11 80 14 14 5 6 45 14 5 35 14 35

Drawing Atomic Structures PROTONS (P+) + NEUTRONS = ATOMIC MASS For example: p + n = atomic mass An element with atomic number 17, how many neutrons does it contain? If p + n = am, then 17 + n = 35 – 17 n = 18

An element with atomic number 17, how many neutrons does it contain? If p + n = am, then 17 + n = 35 en = 35 – 17 e 3 rd P= 3 What is n? n = 18 e- e- If p + n = am 3+n=7 n=7– 3 N=4 -----------------p = 80 80 + n = 201 – 80 n = 121 -----------------p = 82, 82 + n = 207 – 82 n = 125 2 nd ee- e- 1 st e- e- ee- e- e-

Valence Electrons • Each energy level can hold a specific number of electrons. • For example. The 1 st energy level can hold 2 electrons. e • The 2 nd and 3 rd eenergy levels can hold up to 8 electrons each. 3 rd e- e- 2 nd ee- e- 1 st eeee- e- e-

Atomice- Structure: eee- e- 4 th shelle- e- 2 nd ee- e- p+ p+ p+ n p+p+ p+ p+ n p+p+ p+ ee- 3 rd Shell, e- or Orbit ee- e- nn n n nn n 1 st orbit n nn nn n e- e- e- ee- e-

Nucleus= MOST of the MASS is located here! REMEMBER PROTONS + NEUTRONS = ATOMIC MASS e 3 rd eee- 2 nd ee- 1 st e- e- eee- e-

ATOMIC STRUCTURE Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. • first shell a maximum of 2 electrons • second shell a maximum of 8 electrons • third shell a maximum of 8 electrons

SUMMARY 1. The Atomic Number of an atom = number of protons in the nucleus. 2. The Atomic Mass of an atom = number of Protons + Neutrons in the nucleus. 3. The number of Protons = Number of Electrons. 4. Electrons orbit the nucleus in shells. 5. Each shell can only carry a set number of electrons.