Drill #18 Jan. 8 & 9, 2013

• Take your time, do your own work, and draw the Lewis structure for HCN.

• Now, tell me the shape of this molecule.

Agenda• Molecular Geometry Quiz• Review Practice Problems• Review Worksheet – due on Friday!

Objectives• For a complete listing of Midterm

objectives, see the Midterm County Assessment Teacher’s Guide.

Topics Covered• Chapter 1 (Measurements)• Chapter 2 (Energy & Matter)• Chapter 3 (Atomic Structure)• Chapter 4 (Electron Configurations)• Chapter 5 (The Periodic Table)• Chapter 6 (Groups of Elements)• Chapter 7 (Chemical

Bonding/Formulas)• Chapter 8 (Shapes of Molecules)

Chemistry Midterm Review

Practice Problem• Identify the number of protons,

neutrons, and electrons in the following ion: 34Cl1-

Answer• 17 protons; 18 electrons; 17

neutrons

Practice Problem• Identify the number of significant

figures in the following measurements: (a) 2.0045 meters; (b) 0.00045 seconds; (c) 8.00200 ms; (d) 4500 cm

4 rules for determining sig figs

• Non-zero numbers are always significant

• Zeros between non-zero numbers are always significant

• Zeros that act as placeholders are not significant0.0253 has 3 sig figs4320 has 3 sig figs

• All zeros at the end are significant when there is a decimal point after an integer6.20 has 3 sig figs

Answers a) 5

b) 2 c) 6

d) 2

• Convert 254 cm to meters• Convert 60 mg to kg

King Henry Does Usually Drink Chocolate Milk

Base

Kilo hecto deka UNIT deci centi milli

Practice Problems

Answers• 2.54 m• 0.000060 kg

Practice Problem• Identify the number of protons,

neutrons, and electrons in the following ion: 59Ni2+

Answers• 28 protons

• 31 neutrons

• 26 electrons

Practice Problem• Write the electron configuration

using both sublevel notation and orbital diagram notation for sulfur.

Answer• 1s22s22p63s23p4

Practice Problem• Which atom has the larger

atomic radius: Ca, Sr, or Ba? Why?

• Which atom has the greatest ionization energy: Ca, Sr, or Ba? Why?

Answers• Barium (Ba) – largest radius

• Calcium (Ca) – greatest ionization energy

Review• What is an isotope?

• What is an ion?

Review• Isotope = atoms of a particular

element contain the same number of protons but may have a distinct number of neutrons.

• Ion = atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative charge.

Practice Problem• Write the electron configuration

using sublevel notation for strontium (Sr).

Answer• 1s22s22p63s23p64s23d104p65s2

Practice Problem• Write the formulas for the

following: (a) barium carbonate, (b) sodium phosphate, and (c) carbon tetrachloride

Answers• a) BaCO3

b) Na3PO4

c) CCl4

Review Question• Name the following compound:

• Cu(BrO3)2

Answer• Copper(II) bromate

Homework• Complete page 1 of Review Sheet• Due on Thursday!