Chemistry: Unit 3 - The Atom Name:Period:

3.9 - REVIEW – The Atom1. Give the contribution made to the modern atomic theory:

a. Democritus

First person to propose the idea of the atom

b. Aristotle

claimed there were only 4 elements

c. Dalton

Father of the modern atomic theory. Came up with the 5 principles of atoms.

d. Lavoisier

Father of modern chemistry, called H and O elements

e. Thomson

Found atoms contained negatively charged particles known as electrons. Plum Pudding Model

f. Rutherford

Identifed the nucleus of the atom using the Gold Foil Experiment

g. Bohr

Suggested the planetary model of the atoms with electron orbits

h. Moseley

used x-rays to discover each element has a unique number of protons

i. Chadwick

discovered the neutron

2. There are 3 kinds of particles in the atom: the proton, neutron,

and the electron. The symbols and charges of these particles are 1 p 1 or p + , 0 e -1 and 1 n 0 or n 0 . Two of these particles have

about the same mass, the proton and the neutron. The electron

is considerably lighter than the other two.

3. Atoms of the same element that differ in mass are called isotopes.

4. The atomic number equals protons. The mass number equals the

Protons + neutrons.

5. A specific atom with mass number attached, such as Li-7, is called a nuclide.

6. An atom of fluorine has 7 electrons in its outer shell. It has 2 electrons in the inner shell.

7. John Dalton is considered the Father of the Modern Atomic Theory. His theory had some flaws and had to be revised over the years. These flaws are

1. He did not account for isotopes. Atoms of the same element with a different mass.

2. He did not believe atoms could be divided into smaller partilcles.

8. Hydrogen has 3 isotopes, protium, deuterium, and tritium. They have 0, 1, and 2 neutrons in the nucleus, respectively.

9. In Rutherford’s experiment, alpha particles were “shot” at gold foil. These particles are actually the nuclei of the element Hellium. He concluded that the atom is mostly space. and that there is a small, psotively charged “core”, which is now called the nucleus.

10. Fill in the following chart:

Nuclide Atomic Mass #p+ #n #e K shell L shell M shell

Number Number

H3 1 3 1 2 1 1 0 0

Phosphorus 15 32 15 17 15 2 8 5

Fluorine 9 17 9 8 9 2 7 0

11. There are 3 major types of nuclear radiation. Describe each:

alpha radiation

α; actually He atoms and represented 4He2; 2 protons and 2 neutrons; 2p+ are attracted to negatively charged plate

beta radiation

β; emission of high speed e- with a -1 charge; 0e-1;

gamma rays

high energy radiation w/ no electrical charge and no mass

12. Give the nuclear symbols for each particle:

a. neutron - b. electron c. proton

1n00

e-11p1

13. Complete these nuclear reactions:

a. 201Hg80 + 0e1 _201Au79_ b. 226Ra88 222Rn86 + 4He2

c. 11C6 0e1 + 11B5 d. 239Pu94 + 4He2 242Cm96 + 1n0

Perform the following mole calculations

14. Determine the number of grams in 3.92 moles of magnesium

15. Determine the number of moles in 124.8 g of oxygen gas.

16. How many atoms are in 4.6 moles of calcium?

17. Change 23.8 grams of NH3 into number of molecules.

18. Larry and Louise performed the water experiment with these results:

mass of cup with water 63.49 g

mass of cup and water after sipping 41.33 g

Calculate the number of molecules of water in the sip.