Question

q8. (2 points) the low energy color of uv, called ___, is often emitted by the black lamps in tanning beds. the photons will penetrate bare skin to a shallow depth / deeply (circle one) causing free radical damage to skin cells.
q9. (2 points) calcium is in group ___ of the periodic table, and therefore its lewis dot diagram is:

q10. (3 points) show calculation of the photon energy for light from a green laser that has “λ = 532 nm” sketch one the side: (hint: do unit conversions, show units)
λ = 532 nm × = m.
e_ph=

q12. (1 point) true / false (circle one): x - rays travel at a greater speed than visible colors of light because of higher photon energy.

Explanation:

Step1: Answer Q8

The low - energy color of UV is UVA. Photons of UVA penetrate bare skin to a shallow depth.

Step2: Answer Q9

Calcium is in group 2 of the periodic table. Its Lewis - dot diagram has 2 valence electrons represented as two dots around the symbol Ca.

Step3: Answer Q10

First, convert wavelength from nm to m. Since 1 nm = 10⁻⁹ m, for $\lambda=532$ nm, $\lambda = 532\times10^{-9}$ m.
The energy of a photon is given by the formula $E_{ph}=h
u$, and since $
u=\frac{c}{\lambda}$, then $E_{ph}=\frac{hc}{\lambda}$, where $h = 6.626\times10^{-34}$ Js and $c = 3\times10^{8}$ m/s.
$E_{ph}=\frac{6.626\times10^{-34}\text{ Js}\times3\times10^{8}\text{ m/s}}{532\times10^{-9}\text{ m}}\approx3.74\times 10^{-19}$ J

Step4: Answer Q12

False. All electromagnetic waves, including X - rays and visible light, travel at the speed of light $c = 3\times10^{8}$ m/s in a vacuum. The energy of a photon is related to its frequency ($E = h
u$) and not its speed.

Answer:

Q8: UVA; shallow depth
Q9: 2; Ca with 2 dots around it
Q10: $\lambda = 532\times10^{-9}$ m; $E_{ph}\approx3.74\times 10^{-19}$ J
Q12: False