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CHEM 120 EXAM 3 REVIEW GUIDE
If you have a 4 kg sample of this radioisotope (from above) how many grams will remain after the 3 half-
lives have passed?
Answer:
Initially 4 kg
1st HL 2 kg
2nd HL 1 kg
3rd HL 0.5 kg
So I have 0.5 kg after 3 half-lives. I divided by two for each half life. I had three half-lives, so I divided by
Two thrice.
I have a sample of Oxygen-18 with a half life of 5 minutes. How many grams of a 8 gram sample will
remain after 10 minutes?
Answer:
Two half lives have passed: 10 min/5 min = 2 half
lives.Initial 8 grams
1st HL 4 grams
2nd HL 2 grams
Therefore, after 10 mins, 2 grams of Oxygen-18 will remain.
Applications/risks of radiation
Ionizing Radiation: Radiation that can cause atom/molecules to become ions.
Examples of ionizing: X-Rays, gamma rays, alpha particles, beta particles, and higher frequency of UV
raysNon-Ionizing Radiation: Radiation that CANNOT cause atom/molecules to become ions.
Examples of non-ionizing: microwaves, radio waves, visible light, IR radiation, radar….
Particulate radiation: radiation with resting mass
Examples: Alpha, Beta particles (electron), Beta particles (positron)
EM (electromagnetic) radiation: radiation without resting mass
Examples: gamma, visible light, radio waves, X-rays, UV rays, IR radiation, microwaves
, Gamma decay is the most dangerous because as a high energy ray without mass, this type of radiation can
penetrate deeply into our bodies. Alpha is the least dangerous as alpha particles are large and have
difficulty entering our bodies.
Applications of radioactive isotopes: Cancer treatment, typhoid therapy, x-ray, imaging, PET, CT, energy,
irradiation of food to prevent spoiling, etc…
Dangers of radiation: Hair loss, cancer, weight loss, nausea, gastro problems, DEATH
Biochemistry
Four biological macromolecules:
1. Carbohydrate
2. Lipids
3. Proteins
4. Nucleic Acids
Carbohydrates
Chemical structure: In our bodies, carbohydrates form rings. Many OH groups (make them soluble in
water). In their straight form, they contain aldehydes and ketones.
Types:
Monosaccharides: Just one ring (sugar)
• Glucose
• Ribose
• Fructose
• Galactose
Disaccharides: Two rings joined (sugar)
• Lactose
• Sucrose
• Maltose
Polysaccharides: Many rings joined (complex carbohydrates)
• Starch
o Glycogen (very branched, found in animals)
o Amylose (strait, found in plants)
o Amylopectin (branched, found in plants)
• Cellulose (Dietary fiber, structure)
CHEM 120 EXAM 3 REVIEW GUIDE
If you have a 4 kg sample of this radioisotope (from above) how many grams will remain after the 3 half-
lives have passed?
Answer:
Initially 4 kg
1st HL 2 kg
2nd HL 1 kg
3rd HL 0.5 kg
So I have 0.5 kg after 3 half-lives. I divided by two for each half life. I had three half-lives, so I divided by
Two thrice.
I have a sample of Oxygen-18 with a half life of 5 minutes. How many grams of a 8 gram sample will
remain after 10 minutes?
Answer:
Two half lives have passed: 10 min/5 min = 2 half
lives.Initial 8 grams
1st HL 4 grams
2nd HL 2 grams
Therefore, after 10 mins, 2 grams of Oxygen-18 will remain.
Applications/risks of radiation
Ionizing Radiation: Radiation that can cause atom/molecules to become ions.
Examples of ionizing: X-Rays, gamma rays, alpha particles, beta particles, and higher frequency of UV
raysNon-Ionizing Radiation: Radiation that CANNOT cause atom/molecules to become ions.
Examples of non-ionizing: microwaves, radio waves, visible light, IR radiation, radar….
Particulate radiation: radiation with resting mass
Examples: Alpha, Beta particles (electron), Beta particles (positron)
EM (electromagnetic) radiation: radiation without resting mass
Examples: gamma, visible light, radio waves, X-rays, UV rays, IR radiation, microwaves
, Gamma decay is the most dangerous because as a high energy ray without mass, this type of radiation can
penetrate deeply into our bodies. Alpha is the least dangerous as alpha particles are large and have
difficulty entering our bodies.
Applications of radioactive isotopes: Cancer treatment, typhoid therapy, x-ray, imaging, PET, CT, energy,
irradiation of food to prevent spoiling, etc…
Dangers of radiation: Hair loss, cancer, weight loss, nausea, gastro problems, DEATH
Biochemistry
Four biological macromolecules:
1. Carbohydrate
2. Lipids
3. Proteins
4. Nucleic Acids
Carbohydrates
Chemical structure: In our bodies, carbohydrates form rings. Many OH groups (make them soluble in
water). In their straight form, they contain aldehydes and ketones.
Types:
Monosaccharides: Just one ring (sugar)
• Glucose
• Ribose
• Fructose
• Galactose
Disaccharides: Two rings joined (sugar)
• Lactose
• Sucrose
• Maltose
Polysaccharides: Many rings joined (complex carbohydrates)
• Starch
o Glycogen (very branched, found in animals)
o Amylose (strait, found in plants)
o Amylopectin (branched, found in plants)
• Cellulose (Dietary fiber, structure)
