First Semester Final Exam 2013
Chemist: __________________________
Unit 2: Atomic Structure and Periodicity
1. What is the charge, location and mass of a proton?
positive charge, in the nucleus, 1 amu. Determines the identity of the element. P + N = atom’s
mass
2. What is the charge, location and mass of a neutron?
Neutral charge, in the nucleus, 1 amu, # varies in individual atoms of the element to form
isotopes, P + N = atom’s mass
3. What is the charge, location and mass of an electron?
negative charge, arranged in energy levels around the nucleus, negligible mass. Determines the
chemical properties of the element. The valence electrons are the electrons that are involved in
bonding.
4. What is an energy level? “layers” around a nucleus where the electrons are located
How can you determine how many an element has? By what row the element can be found on the
periodic table. For example, Mg is on the 2nd row and it has 2 energy levels.
5. What atomic particle determines the identity of the element? Protons (if the Proton # changes it is a
different element)
6. What atomic particle is active in bonding and determines the chemical properties of the atom?
Electrons (the valence electrons are shared or stole/transferred in chemical bonds)
7. Define “atomic number” the # of protons in an atom
8. Where is an atom’s atomic number on the periodic table? above the symbol
9. Define “atomic mass” the # of protons + the # of neutrons in an atom. (electrons’ mass is so small it
does not affect the overall mass…it’s like having long hair vs short hair; you still say you weigh the
same)
10. Where is an atom’s atomic masss on the periodic table? below the symbol
11. What is the different between atomic mass and average atomic mass? The # on the periodic table is
the average mass of all the isotopes of that element. An individual atom’s mass is always a whole
number that represents the # of protons and neutrons that specific atom has.
12. Define “isotope” atoms of the same element that have different masses (same # of protons but
different # of neutrons). Some isotope nuclei are unstable; these are radioactive isotopes and will
decompose after a certain period of time (2 sec to 5000 years depending on the isotope).
13. Define “ion” a charged atom caused by the gain or loss of electrons.
14. Define “cation” a positive ion. Metals lose electrons and become positively charged ions.
15. Define “anion” a negative ion. Non-metals gain electrons and become negatively charged ions.
16. Define “period” a row in the periodic table. Atoms in the same period have the same # of shields
and energy levels.
17. Define “group/family” a column in the periodic table. Atoms in the same family have the same # of
valence electrons and similar chemical properties.
What are the general characteristics of Group 1/Alkali Metals?
Metals, 1 valence electron, highly reactive (remember the Li, Na, K and water demos?!)
What are the general characteristics of Group 2/Alkaline Earth Metals?
Metals, 2 valence electrons, reactive (not quite as reactive as Group 1 – remember the Ca and
water demo)
What are the general characteristics of Group 7/Halogens?
Non-metals, 7 valence electrons, reactive, most are gases at room temperature, most are diatomic
What are the general characteristics of Group 9/Nobel Gases?
Non-metals, 8 valence electrons, non-reactive (inert), gases at room temperature
18. Where are the metals, transition metals, metalloids and non-metals located on the periodic table?
Metals are anything to the left of the staircase. Transition metals are metals that are located in
the short middle part of the periodic table. Non-metals are located to the right of the staircase
19. What are the properties of metals?
Metals conduct electricity and heat, they have luster (are shiny) and are malleable (can be molded
into various shapes). They have low electronegativities and ionization energies which cause them
to lose electrons and become cations (positive electrons).
20. What are the properties of metalloids?
Metalloids are elements that are located on both sides of the staircase that have properties of
both metals and non-metals.
21. What are the properties of non-metals?
Non-metals do not conduct electricity or heat, are dull and brittle if solid at room temperature.
Many are gases at room temperature. They have high electronegativities and ionization energies
which cause them to gain electrons and become anions (negative electrons).
22. Define “shielding” the inner energy levels that block a nucleus’s ability to pull its valence electrons
and other shared electrons towards the nucleus.
How does shielding change as you move across a row on the periodic table? Atoms in the same row
have the same # of shields. (Elements in the 3rd row of the periodic table have 2 shields and 1 row
of valence electrons.)
How does shielding change as you move down a column on the periodic table? Shielding increases as
you move down a column. (Elements in the 4th row of the periodic table have 3 shields and 1 row of
valence electrons.)
23. Define “nuclear charge” the pull that the protons can exert on the atom’s electrons. The more
protons an atom has the stronger the nuclear charge / proton pull.
24. Define “atomic radius” the distance from the center of the nucleus and the valence energy level.
How does atomic radius change as you move across a row on the periodic table? decreases
Why? Same # of shields but more protons as you move to the right across the table. The
increased protons are able to pull the valence electrons closer to the nucleus.
How does atomic radius change as you move down a column on the periodic table? increases
Why? Each row of the periodic table adds an energy level to the atoms. This means that there
is another shield that counters the extra protons. The valence electrons are able to move farther
away from the nucleus.
25. Define “Ionization energy” the energy 1 atom needs to remove the 1st valence electron from
another atom
How does Ionization energy change as you move across a row on the periodic table? increases
Why? As the # of protons increase they are able to pull the valence electrons towards the
nucleus, thus requiring more energy to pull 1 valence electron away.
How does Ionization energy change as you move down a column on the periodic table? decreases
Why? As the # of shields increase the nucleus can’t pull the valence electrons as well thus
requiring less energy to pull 1 valence electron away.
26. Define “Electronegativity” an atom’s ability to pull shared valence electrons towards its nucleus
How does Electronegativity change as you move across a row on the periodic table? increases
Why? As the # of protons increase atoms are able to pull shared electrons towards it own
nucleus
How does Electronegativity change as you move down a column on the periodic table? decreases
Why? As the # of shields increase the nucleus can’t pull shared valence electrons as well
27. Define “Reactivity” how readily an atom will react with another
What is the most reactive metal? Francium Why? Fr has the lowest Ionization energy of all
metals. Makes it the quickest to lose its 1 valence electron. So reactive it is impossible to find
it pure in nature – it is always bonded to another atom.
What is the most reactive non-metal? Fluorine Why? F has the highest electronegativity of all
non-metals. Makes it the best at pulling valence electrons in to gain 1 valence electron to
complete valence energy level.
28. What are the 2 conclusions Rutherford made about the structure of the atom after his Gold Foil
Experiment? When most of the + particles were able to pass through the Gold foil, Rutherford
concluded that most of the atom is empty space. 1 time in 8000 the + particles were deflected.
Rutherford concluded that the gold’s positive charges are clumped in a small nucleus.
29. What is the mass of the atom? 35 amu How many protons does it have? 17 protons
How many neutrons does it have? 35-17=18 neutrons
How many electrons does it have? No charge notated on upper right corner. Electrons = protons; 17
electrons
How would the symbol change if this atom gained an electron?
(17 protons, 18 electrons)