Discussion worksheet- Atoms, Isotopes, and Unit Conversions-week1 PDF

Preview

Summary

discussion worksheet answer key...

Description

Discussion Worksheet: Atoms, Isotopes, and Unit Conversions 1. Decide whether the following are chemical changes (C) or physical changes (P). Circle the letter of your response. (a) Solid CO2 sublimes to gaseous CO2 (b) Natural gas (methane) burns (c) Liquid oxygen evaporates (d) Sodium metal burns when put into water (e) HCl neutralizes NaOH, producing heat (f) Hydrogen gas forms when copper metal is added to a solution of HCl (g) Barium melts at 725 oC. (h) Solid AgCl forms when solutions of AgNO3 and NaCl are mixed (i) Water vapor condenses on cold surfaces (j) Aluminum metal can be hammered into thin sheets!! 2. How many significant figures are in each number. a. 3.20 x 10-6___________ b. 1.30 _______________ c. 0.001125 ___________ d. 5.0003 _____________ e. 45000 ______________ 3. Express each number in scientific notation a. 315,171,000 ________________ b. 0.000000087 _______________ c. 0.145 _____________________ 4. Express each number in decimal notation a. 4.2 × 10-3 ___________________ b. 9.523 × 105 _________________ c. 1.18 × 10-7 __________________ 5. Calculate to the correct number of significant figures. a.

56.55 × 0.920 ÷ 34.2584 =

b.

0.987 +125.1 – 1.22 =

c.

(4.58 ÷ 1.239) – 0.578 =

C C C C C C C C C C!!

P P P P P P P P P P

6. Fill in the blanks to complete the table. Symbol Si

Atomic number 14

S2-

Mass number

# of protons

# of electrons 14

# of neutrons 14

Charge

2-

32

Cu2+

34 15

15

2+

16

7. In the table below, check off all of the categories that can be used to describe the elements listed.

Element! Metal! Nonmetal! Semimetal!

Noble! gas!

Halogen!

Transition! Alkali!Earth! Alkali! Metal! Metal! Metal!

Rb!

!

!

!

!

!

!

!

!

Rn!

!

!

!

!

!

!

!

!

Ra!

!

!

!

!

!

!

!

!

Ru!

!

!

!

!

!

!

!

!

Te!

!

!

!

!

!

!

!

!

Ti!

!

!

!

!

!

!

!

!

Si!

!

!

!

!

!

!

!

!

Pb!

!

!

!

!

!

!

!

!

8. An element has four naturally occurring isotopes with the masses and natural abundances given here. Find the atomic mass of the element and identify it. Isotope 1 2 3 4

Mass (amu) 135.90714 137.90599 139.90543 141.90924

Abundance (%) 0.19 0.25 88.43 11.13

9. The mass of a proton is 1.67 × 10-27 kg. What is the mass of a proton in picograms?

10. Perform each unit conversion: a) 3.5 L to qt

b) 815 yd to km

11. How many carbon atoms are there in a diamond (pure carbon) with a mass of 52 mg?

12. What is the mass of 4.75 ×1024 aluminum atoms?

13. Calculate the number of moles of sulfur in 57.8 g of sulfur....