Download Atomic Theory Review Sheet

Name____________________________
Atomic Theory Review Sheet
Complete the following chart..
PARTICLE
proton
neutron
electron
CHARGE
Positive
Neutral
Negative
MASS
1 amu
1 amu
0 amu
LOCATION
Nucleus
Nucleus
Electron Cloud
Define the following terms:
1. Atom – the smallest part of an element that still retains the properties of that element
2. Isotope – occurs when atoms of the same element have a different number of neutrons
3. Atomic number – determines the identity of an element, number of protons & electrons
4. Mass number – the total number of protons and neutrons in the nucleus of an atom
5. Average Atomic mass – the average mass of the isotopes of an element
Short Answer:
6. What is the charge of an atom and why?
Atoms are neutral because the positive protons cancel the negative electrons.
7. Summarize the main concepts of Dalton’s Atomic Theory.
1. All elements are composed of tiny indivisible particles called atoms.
2. Atoms of the same element are identical.
3. Atoms of different elements can physically mix together or combine in simple whole
number ratios.
4. Chemical reactions occur when atoms are separated, joined or rearranged, but atoms of
one element are never changed into another element as a result of a reaction.
8. Which parts of Dalton’s theory are no longer accepted and why?
Atoms are now known to be divisible.
9. Experiments with a cathode ray tube led to the discovery of the _____electron____.
10. Explain how Rutherford’s gold foil experiment worked, and what it proved.
Rutherford shot radioactive particles through gold foil onto photo paper. He expected all the
particles to go straight through, but some bounced back. This told him that there was a
positively charged, very dense center called the nucleus.
11. What determines the identity of an atom?
The atomic number or number of protons identifies it.
12. Define the law of definite proportions.
States that any sample of a compound always has the same composition.
13. Define the law of multiple proportions.
States that elements always combine in simple whole number increments; ex) H2O & H2O2
14. Define the law of conservation of mass.
States that mass can’t be created or destroyed; mass is never gained or lost in a reaction.
15. What do isotopes of the same element have in common and what is different?
Isotopes have the same atomic number, # of protons & # of electrons.
Isotopes have different mass numbers and # of neutrons.
16. An element has 19 protons, 19 electrons and 20 neutrons. It has an atomic number of __19_ and a
mass number of __39__? What is the identity of this element?___potassium_____
17. An element has 8 protons, 8 electrons and 8 neutrons. It has an atomic number of __8_ and a mass
number of __16__? What is the identity of this element? _____oxygen_____
18. What is the number of protons, neutrons and electrons for:
Chlorine-35 ____17 protons_____, ___18 neutrons___, ____17 electrons____
Argon-40
____18 protons__, ___22 neutrons___, _____18 electrons___
67
30 Zn
___30 protons____, ____37 neutrons__, ____30 electrons____
28
14 Si
___14 protons__, ___14 neutrons___, _____14 electrons____
19. If Chlorine-35 has 18 neutrons, how many electrons does it have? 17 electrons
20. How do you find the following:
A. Number of protons in an atom = ____same as the atomic number______
B. Number of neutrons in an atom = _____mass number – atomic number___
C. Number of electrons in an atom = ______ same as the atomic number____
Symbol
C
Br
P
F
Zn
Atomic
Number
6
35
15
9
30
Mass
Number
14
80
31
19
95
Number of
Protons
6
35
15
9
30
Number of
Electrons
6
35
15
9
30
Number of
Neutrons
8
45
16
10
65