Download Answer Key to Chem Semester 1 Exam Review

Answer Key to Chem Semester 1 Exam Review Questions (Parts 3 & 4)
Pgs. 89-90
1. A. Because all chemical reactions are only the rearrangements of atoms, mass is neither created
nor destroyed in such changes.
B. Atoms of each element have their own characteristic mass, so compounds consisting of these
atoms always have the same composition by mass.
C. Only whole atoms combine in chemical compounds, so different compounds between the
same two elements must result from the combo of different whole numbers of atoms.
2. 5 mass units; 13 mass units
3. A. the smallest particle of an element that retains the chemical properties of that element
B. the nucleus and the surrounding electrons
4.
An electron is negatively charged, has a mass approx. 1/2000 that of a H atom, has a fixed
charge-to-mass ratio, and is present in atoms of all elements.
5. His model had most of the mass in the nucleus. He bombarded gold atoms with positively
charged particles; most went straight through the atom, but some were deflected and a few
bounced back.
6. Atomic number
7. A. atoms of an element that have the same number of protons but different number of neutrons
B. They have the same number of protons and electrons.
C. They have different numbers of neutrons.
8. Isotope
Protons
Electrons
Neutrons
Si-28
14
14
14
Si-29
14
14
15
Si-30
14
14
16
9.A. Its number of protons
B. the total number of protons and neutrons in an isotope
C. atomic = 1; mass = 2
10. any isotope of any element
11. A. helium-4
B. oxygen-16
12. A. carbon-12
B. 12 amu
13. A. 4 amu
B. 54 amu
C. potassium-39
14. A. the number of particles equal to the number of atoms in 12g of carbon-12
C. 6.022 x 1023
B. mol
D. Avogadro’s number
15. A. the mass of one mole of atoms of that element
B. 12.01 g/mol, 20.18 g/mol, 55.85 g/mol, 238.03 g/mol
16. A. divide by molar mass
B. divide by molar mass, then multiply by Avogadro’s #
17. A. 6.94g
B. 27.0g
18. A. 1.000 mol
C. 40.1g
B. 0.5000 mol
D. 55.8g
C. 1.57x103mol
E. 12.01g
F. 107.9g
D. 2.81x10-13mol
19. 39.95 amu
20. 10.00 amu
21. A. 9.03x1023 atoms
22. A. 9.500g
E. 7.6x10-21g
B. 4.068x1024 atoms
C. 1.50x1023 atoms
C. 2.65x10-10g
B. 6.05g
D. 1.12x10-3g
F. 3x10-22g
23. A. 3.01x1023 atoms
D. 7.872x1019 atoms
B. 1.51x1023 atoms
C. 2.31x1022atoms
E. 3.06x1011 atoms
Pg. 124
1. Gamma rays, x rays, UV light, visible light, infrared, microwaves, radio waves; 3.00x108 m/s
2. Light’s wavelike properties include frequency and wavelength as well as the ability to interfere
and diffract. It’s particle-like properties when it is absorbed and emitted by matter in
phenomena such as the photoelectric effect, emission of light by hot objects, and the lineemission spectra of elements.
3. Frequency ranges from approx. 4.29x1014 to 7.50x1014 Hz. Wavelength ranges from 400 – 700
nm.
4. Red, orange, yellow, green, blue, violet
5. The wave theory could not explain the photoelectric effect of hydrogen’s line-emission
spectrum.
6. A. c = λv; λ is wavelength and v is frequency and c is velocity
B. E = hv; E is energy, h is Planck’s constant, and v is frequency
C. E = hc/λ
7. A. wave theory
B. particle theory
C. particle theory
8. The ground state of an atom is the lowest energy state. An excited state of an atom is any energy
state that is higher in energy than the atom’s ground state is.
9. a line-emission spectrum is produced when an electron drops from a higher-energy orbit to a lowerenergy orbit, emitting a photon. The photon’s energy is equal to the difference in energy between the
two levels.
10. 7.05 x 1016 Hz
11. 2.35 x 10-16 J
12. E = hc/λ
13. 267s
14. 1.99 x 10-13 J