PHYS 183 Lecture Notes - Lecture 11: Electromagnetic Spectrum, Mass Number, Atomic Number

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2 Feb 2013

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Electromagnetic spectrum is all of the light in the universe we can only see the visible spectrum. Gamma rays have high frequency; radio waves have low frequency. Blue light is higher energy, shorter wavelength than red light: blue is closer to gamma rays, red is closer to radio waves. Nucleus contains positively charged protons and neutral neutrons; cloud of electrons surround the nucleus. Most of the mass in the atoms is in the nucleus. Elements can come in different isotopes different number of neutrons: c-12 has 6 protons + 6 neutrons; c-13 has 6 protons + 7 neutrons; c-14 has 6 protons + A molecule is made up of 2 or more atoms which are bound together chemically share electrons ie/ h2o = 2 h + 1 o. 3 phases of matter: gas water vapour, solid ice liquid water. Each phase has different chemical bonds but are made of the same thing.

Related Questions

A nuclear reaction is represented by an equation similar to theequation for a chemical reaction. An example of a nuclear reactionis the decay of radium into radon by the emission of an alphaparticle (a helium nucleus). The equation for this reactionis

^{226}_{\ 88}{\rm Ra}\; \rightarrow \, ^{222}_{\ 86}{\rmRn}+\;^4_2{\rm He}.

The superscript preceding each element indicates the nucleon numberof that particular nucleus (total number of protons and neutrons).The subscript indicates the charge of the nucleus, which is equalto the atomic number for nuclei. Nuclear reactions frequentlyinvolve electrons (sometimes called beta rays) and photons(sometimes called gamma rays). Electrons, which have nucleon number0 and charge -1, are represented in equations as either ^{\ \;0}_{-1}\beta or ^{\ \; 0}_{-1}{\rm e}. Photons are represented as^{0}_{0}\gamma to emphasize that they have no nucleon number andcarry no charge.

In nuclear reactions, several conservation laws are usuallysufficient to determine the products or reactants. One of these isconservation of nucleon number. The total number of neutrons andprotons in all of the reactants must be the same as the totalnumber of protons and neutrons in the products. Although protonsand neutrons sometimes change into one another, neither can simplydisappear. Another important conservation law is conservation ofcharge. The net charge of the reactants must be the same as that ofthe products.

Notice that, in our equation for the decay of radium, the sum ofthe nucleon numbers on each side is 226 and the sum of the chargeson each side is 88. If you knew everything in this equation exceptthe isotope of radon produced, you could simply subtract 4 from 226to find the nucleon number required to make the nucleon number ofthe products equal the nucleon number of the reactants. Similarly,if you knew everything in this equation except for the identity ofthe product element, you could simply subtract 2 from 88 and thenlook in a periodic table to find that the element with atomicnumber 86 is radon.

In parts A and B consider the decay of radon by alpha particleemission:

^{222}_{\ 86}{\rm Rn}\;\rightarrow\;X +\,^{4}_{2}{\rm He}.

a. What is the nucleon number of the element X?
Express your answer as an integer.

b. What is the atomic number (nuclear charge) of the elementX?
Express your answer as an integer.

n parts C and D consider the decay of Potassium-43 into calcium-43via the following reaction:

^{43}_{19}{\rm K} \rightarrow ^{43}_{20}{\rm Ca}+\,X.

c. What is the charge of the emitted particle X?
d. is not visible yet

E. An isotope of potassium with a half-life of roughly one billionyears is often used in radioactive dating. This isotope decaysthrough electron capture, the process of drawing an electron intothe nucleus. What is the chemical symbol for the element thatresults from this process? The equation for the reaction is

^{40}_{19}{\rm K}+\,^{\ \;0}_{-1}{\rm e}\rightarrow \,?.
Express your answer as a chemical symbol (e.g., Na forsodium).

f. The reaction energy of a reaction is the amount of energyreleased by the reaction. It is found by determining the differencein mass between the reactants and products and then using E=mc^2 toconvert the lost mass into the released energy.

Look again at the equation for the decay of radium (Ra), given inthe introduction. Use the following table of masses to determinethe reaction energy of this reaction.
Nucleus or particle Mass in atomic mass units
radium-226 226.025402
radon-222 222.017571
alpha particle 4.002602
Express your answer in joules to three significant figures.

please answer fully... thank you

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and if u can show me the steps because I will use it asnotes.

1-What are the metric prefixes for ten and tenth?

2-If you multiplied 7774 m by 36 m, how many significant figuresshould you report in your answer?

3-A ball is dropped:
What is its initial speed?
What is the magnitude of its initial acceleration?

4-A jogger jogs two blocks directly north.
(a) How do the jogger's average speed and the magnitude of theaverage velocity compare?
average speed ( ) magnitude of average velocity
(b) If the jogger's return trip follows the same path, how doaverage speed and magnitude of the average velocity compare for thetotal trip?
average speed ( ) magnitude of average velocity

5-A child's cubic play block has a mass of 115 g and sides of 5.2cm. When placed in a bath tub full of water, will the cube sink orfloat?
(sink) or (float)

6-A ball with a radius of 8 cm and a mass of 550 g is thrown into alake. Will the ball sink or float?
(sink) or (float)

7-Persons A and B do the same job, but B takes longer
Who does the greater amount of work?
person A, person B, Or all the same
Who is more "powerful"?
Person A or Person B

8- Which two renewable energy sources depend on the weather?(Select all that apply.)
geothermal
biomass
tidal
solar
wind

9- The two common liquids used in liquid-in-glass thermometers arealcohol (ethanol) and mercury, which have melting points andboiling points of -114Â°C, 79Â°C and -39Â°C, 357Â°C,respectively.
Which one of these thermometers would be better for low temperaturemeasurements?
(alcohol or mercury)
Which one of these thermometers would be better for hightemperature measurements?
(alcohol or mercury)

10-What determines the phase of a substance? (Select all thatapply.)
humidity
temperature
amount of the substance
pressure

11-What is the difference between a longitudinal wave and atransverse wave?

Longitudinal wave: particle displacement is (---) parallelperpendicular to wave velocity.
Transverse wave: particle displacement is ( ------) perpendicularparallel to wave velocity.

Give an example of a longitudinal wave.
(sound wave in air OR
light wave)
Give an example of a transverse wave.
(sound wave in air Or
light wave)

12-Which end (blue or red) of the visible spectrum has the shorterwavelength?
Which has the lower frequency?

13- How long does the image of a 18-in ruler appear in a planemirror?
Does this depend on the distance the ruler is from themirror?
(Yes OR
No)

14-What optical phenomenon causes soap bubbles and oil slicks toshow colorful displays?

15- Which two particles that make up atoms have about the samemass? (Select all that apply.)
protons
electrons
neutrons

16- Which two have the same magnitude of electric charge? (Selectall that apply.)
neutrons
electrons
protons

17- Name one phenomenon that can only be explained by light havinga wave nature.
polarization
photoelectric effect
acceleration
displacement

18- How are frequency and wavelength of an electromagnetic waverelated?
higher the frequency, longer the wavelength
higher the frequency, shorter the wavelength
the frequency and wavelength are not direclty related

19- What other name is often used to refer to the electron cloudmodel of the atom?
plum pudding model
billiard ball model
quantum model
nuclear model
planetary model

20- What are the names of the elements with the followingsymbols?
(a) Ne
(b) Li
(c) He

21- After 4 half-lives have gone by, what fraction of a sample of aradioactive isotope remains? (Write your answer in fractionform.)

22- What are the most common names for these compounds andions?
(a) N2O
(b) HCl
(c) C2H3O2 ?
(d) PO43-

23- What is the formula for the common household compound known astable salt? (Type your answer using the format CO2 for CO2.)

24- What element has the lowest electronegativity?
What element has the second highest electronegativity?

Give the Stock system name for the following.
(a) Cr(OH)2
(b) CuCl2
(c) AuBr3

PHYS 183 Lecture Notes - Lecture 11: Electromagnetic Spectrum, Mass Number, Atomic Number

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