Welcome to Chem 1A
with Terri Bentzinger
E-mail: benzene4president@gmail.com
Website: http://clas.sa.ucsb.edu/staff/terri/
Drop-in: M thru R, 1-2, SRB Rm 3274
Atoms – Molecules - Ions
1. What does the atomic number tell you about
an atom? What is the atomic number of
sulfur?
Atomic number tells you the number of
protons in any one element – can be found on
the periodic table
Sulfur has an atomic number of 16
Atoms – Molecules - Ions
3. Define mass number. What is the mass
number for potassium?
Mass number is the total number of protons
and neutrons in any one isotope – can not be
found on the periodic table
Since the mass number is not on periodic
table we can not answer the second question
without further resources
Atoms – Molecules - Ions
3. What are isotopes? – Isotopes are atoms of
the same element with varying number of
neutrons
Atoms – Molecules - Ions
4. What is atomic mass for chlorine? How is the
atomic mass calculated? Atomic mass of
chlorine is 35.45 – atomic masses are
calculated by taking the average of the
naturally occurring isotopes based on their
relative abundances
Atoms – Molecules - Ions
5. What are ions? How are ions generated?
Ions are atoms or groups of atoms with a net
charge – Ions are generated by the gain or loss
of electrons – gaining an electron causes a net
negative charge a.k.a. an anion – losing an
electron causes a net positive charge a.k.a. a
cation
Atoms – Molecules - Ions
6. Metals tend to gain or lose electrons?
What charge do group 1 metals form? 1+
What charge do group 2 metals form? 2+
Atoms – Molecules - Ions
7. Non-metals tend to gain or lose electrons?
What charge do group 5 non-metals form? 3What charge do group 6 non-metals form? 2What charge do group 7 non-metals form? 1What charge do group 8 non-metals form? 0
Atoms – Molecules - Ions
8. What’s the difference between elements,
compounds, atoms and molecules? Elements
are the simplest of the pure substances and
can not be chemically broken down –
Compounds are 2 or more elements
chemically bonded to each other – atoms are
the smallest stable particles that make up an
element – molecules are 2 or more
nonmetallic atoms bonded to each other
Atoms – Molecules - Ions
9. Fill in the following table:
Isotope Symbol
Protons
Neutrons
Electrons
Charge
47Ti
22
25
22
0
38Cl
17
19
17
0
42Ca2+
20
22
18
2+
28Al3+
13
15
10
3+
79Br-
35
44
36
1-
111Te2-
52
59
54
2-
Atoms – Molecules - Ions
10. How could you distinguish between ionic
compounds, covalent compounds and acids?
Ionic compounds have a cation and an anion –
the cation is more often than not a metal with
the exception of ammonium ion (NH4+) –
Covalent compounds are made up of 2 or
more nonmetals – Acids start with hydrogen
Atoms – Molecules - Ions
11. The fact that nitrogen and oxygen can form multiple
compounds such as NO, N2O, NO2 and N2O5 is an
example of which law? Law of multiple
proportions
Atoms – Molecules - Ions
12. Name and label the type of compound for
each of the following:
a. LiHCO3 lithium bicarbonate
g. HClO hypochlorous acid
b.
c.
d.
e.
f.
Na2SO3 sodium sulfite
(NH4)3PO4 ammonium phosphate
Fe(OH)3 iron(III) hydroxide
CuBr copper(I) bromide
HF hydrofluoric acid
h. HNO3 nitric acid
i. SF6 sulfur hexafluoride
j. CO carbon monoxide
k. P2O5 diphosphorus pentoxide
l. NCl3 nitrogen trichloride
Atoms – Molecules - Ions
13. Write the chemical formulas for the following
compounds:
a.
b.
c.
d.
e.
f.
g.
h.
calcium cyanide Ca(CN)2
aluminum sulfate Al2(SO4)3
lead(IV) permanganate Pb(MnO4)4
hydrosulfuric acid H2S
sulfuric acid H2SO4
bromous acid HBrO2
sulfur trioxide SO3
carbon tetrachloride CCl4
Atoms – Molecules - Ions
14. Here are some common names that you’re
expected to know; write the chemical formula.
a. Water H2O
b. Methane CH4
c. Ammonia NH3