1. Physical Science
Chapter 4

2. Atoms
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons

3. Atoms

4. Atoms http://www.youtube.com/watch?v=FxDpZ8wGgZ8
History of the atomic theory

5. What is an Atom

6. The parts of the atom are called subatomic particles
Protons, electrons, and neutrons are subatomic particles

7. Positively charged particles found in the nucleus
Protons
Positively charged particles found in the nucleus
Each proton has a charge of 1+
Some nuclei have more than 100 protons

8. Protons

9. Discuss a scientific observation you made this weekend,
Bellwork 9-30
Discuss a scientific observation you made this weekend,
Then…draw an atom with all of its subatomic particles from memory

10. Negatively charged particles found in the space outside the nucleus
Electrons
Negatively charged particles found in the space outside the nucleus
Each electron has a charge of -1

11. Electrons

12. A neutral particle found in the nucleus of an atom
Neutrons
A neutral particle found in the nucleus of an atom
Its mass is almost exactly equal to a proton

13. Neutrons

14. Properties of particles
Protons, electrons, and neutrons can be distinguished by mass, charge, and location in an atom

15. Protons and neutrons have almost the same mass
Takes almost 2000 electrons to equal the mass of one proton
Electron’s charge, however, is equal to that of the proton

16. Periodic table

17. Atomic Mass and Number

18. Atomic Number
Atomic number of an element equals the number of protons in an atom of that element

19. The atomic number also equals the amount of electrons and atom has
Atoms are neutral because they have the same number of electrons and protons
Therefore…
The atomic number also equals the amount of electrons and atom has

20. Atomic number gives the number of protons, nut not the # of neutrons
Mass Number
Atomic number gives the number of protons, nut not the # of neutrons
Mass number is the sum of the protons and neutrons

21. Atom of aluminum has 13 protons and 14 neutrons, what is its mass number?

22. Dalton thought that all atoms of a given element were identical
Isotopes
Dalton thought that all atoms of a given element were identical
Every atom of a given element does have the same amount of protons and electrons,

23. Isotopes
But every atom of a given element does not have the same number of neutrons
Isotopes are atoms of the same element that have different numbers of neutrons and different mass numbers

24. What are some effects of water water that contains hydrogen isotopes?
Look at figure 12 on page 112
What are some effects of water water that contains hydrogen isotopes?

25. With a group of 2-3
1. How are the compositions of heavy water and ordinary water similar?
What type of hydrogen atoms does ordinary water contain?
What type of hydrogen atoms does heavy water contain?
Compare the properties of heavy water and ordinary water.

26. Complete section one and 2 in your workbook
When complete…
Complete section one and 2 in your workbook
What you do not finish in class will be homework

27. Bellwork
How many neutrons are in an atom with an atomic number of 32 and an atomic mass of 68?

28. Atom http://www.youtube.com/watch?v=yqLlgIaz1L0

29. Bohr
Bohr’s model of the atom focused on the electron which is what makes his model the modern model

30. Energy Levels
Electrons move with constant speed in fixed orbits around the nucleus
Each electron has a specific amount of energy
Sometimes atoms gain or lose energy and the energy in an electron can change

31. Energy Levels
Energy levels: The possible energies that an electron can have.
The electrons in an atom can move from one energy level to another when they gain or lose energy

33. How do we know?
Scientists can measure the energy gained when electrons absorb energy and move to a higher energy level
They can also measure the energy released when an electron moves to a lower energy level

34. How do we know?
Some elements emit light when they release energy
Explosions can cause heat which pushes electrons to higher energy levels

35. Electron cloud
The electron cloud model is used to describe the possible locations of electrons around the nucleus.

36. Atomic Orbitals
Orbital is the region of space around the nucleus where the electron is likely to be