Download Chemistry 20 - Unit 1 Exam

Chemistry 20 – Unit 1 Exam – The Atom and Elements
Name_____________
September 17th , 2010
Part A. Match each of the accomplishments from the first column with a name
in the second column. Place the letter of the term in the second
column in the correct blank. Each part is worth one mark.
_____ a column on the periodic table.
_____ helps stabilize the nucleus of an atom.
_____ dense center of an atom.
_____ a particle involved with bonding and giving elements
their properties.
_____ an interpretation of data.
_____ the percentage of an isotope found in nature.
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
abundance
electron
family
inference
isotope
neutron
nucleus
observation
period
proton
valence
electron
_____ a row on the periodic table.
_____ a negatively charged particle in an atom.
_____ data taken by using your senses.
_____ a particle in an atom that defines an element.
Part B. Multiple Choice. Choose the best answer that fits the questions or
statements below. Each is worth 1 mark.
1. Who is credited with the founding of the modern periodic table?
A. J.J. Thomson
B. Dimitri Mendeleev
C. John Dalton
D. Earnest Rutherford
2. The electron was discovered by_____.
A. J.J. Thomson
B. Dimitri Mendeleev
C. John Dalton
D. Earnest Rutherford
3. The nucleus of the atom was discovered by_____.
A. J.J. Thomson
B. Dimitri Mendeleev
C. John Dalton
D. Earnest Rutherford
4. The experiment leading to the discovery of the electron involved a(n) ____.
A. cathode ray tube
B. oil drop
C. thin sheet of gold foil
D. none of the above
5. Which scientist believed the atoms of elements had differed in their
weights?
A. Aristotle
B. Democritus
C. John Dalton
D. Earnest Rutherford
6. Which family does the element bromine belong to?
A. Alkali metals
B. Alkaline earth metals
C. Halogens
D. Noble gases
7. A substance that is a poor conductor of electricity is most likely a _____.
A. metal
B. metaloid
C. nonmetal
D. semiconductor
8. Which of the following is not a property of a metal?
A. brittle if solid
B. ductile
C. malleable
D. shiny when polished
9. The modern periodic table is organized by ____.
A. atomic number
B. chemical and physical properties
C. atomic mass
D. all of the above
10. The electrical conduction of semiconductors ____ with an increase in
temperature.
A. stays the same
B. increases
C. decreases
D. is insignificant
Part B. Short Answer. Answer each of the following questions. Each question
is worth a different amount of marks, so read the questions carefully.
1. Explain what the mass number is for an atom. What are atoms of the
same element with differing mass numbers called? Why can these
different types of atoms exist?
2. Explain why the atomic radius decreases as you go from left to right
across a period, even though the number of electrons increases. Explain
how the atomic radius changes as you move down a family and why.
3. Fill in the chart below. Atoms are neutral unless indicated otherwise.
(14 marks: each box is worth 0.5 marks)
Element
name
Isotope
symbol
25
12
Atomic
Number
Mass
Number
15
31
# of
protons
# of
electrons
Charge
Mg2+
18
82
Mercury
# of
neutrons
124
202
0
54
82
1+
4. Boron has isotopes with masses 10 amu and 11 amu with abundances of
19.77% and 80.23%, respectively. What is the average atomic mass of
boron? Put your answer to 2 decimal places.
5. How many valence electrons are in the atom with an electron
configuration of 1s22s22p4? If this atom were neutral, how many protons
would it have and what element would it be?
6. Write the full electron configuration for the following: (1 mark each)
a) He
b) Ca
7. Given the configuration of the last sublevel, name the element that
would correspond to the electron configuration assuming the atom is
neutral: (1 mark each)
a) 3s1
b) 1s1
8. Write the noble gas electron configuration for the following: (1 mark each)
a) As
b) Sn
9. Draw the orbital notation for the following: (2 marks each)
a) O
b) S2-
10. A friend, while studying for this exam, told you that only one element
can have the electron configuration of 1s22s22p63s23p6. Under what
circumstance is your friend wrong? State the obvious element, and then
two other atoms it could represent. (4 marks)