Flashcards in Chapter 2: Chemical Level Of Organization Deck (138)
How many chemical elements are present in your body?
What are the 4 major elements that constitute 96% of your body mass?
O, C, H, N
What are the 8 elements that constitute 3.6% of your body mass?
Ca, P, K, S, Cl, Mg, Fe, and Na
How many trace elements are in your body?
What is the nucleus?
The dense core of an atom
How many electrons do the first 3 shells hold?
First holds 2, second holds 8 and third holds 18
Why is an atom usually electrically neutral?
Because the number of protons equals the number of electrons
What is the atomic number and atomic mass?
Atomic number is the number of protons. Atomic mass is the number of protons + neutrons
What are isotopes?
Atoms that have different numbers of neutrons so have different mass numbers
What is a stable isotope?
It's nuclear structure doesn't change over time.
What's a radioactive isotope? Give some examples
Unstable. Their nuclei decay into stable configuration (H-3, C-14, O-15, O-19)
Explain how radioactive isotopes can be harmful
They can break apart molecules thus posing a threat to human body by producing tissue damage or causing various types of cancer
Name some benefits of radioactive isotopes
For diagnostic or treatment purposes. Used as tracers to follow movement of certain substances through the body. Iodine-131 detects cancer of thyroid gland. Cesium-137 used to treat advanced cervical cancer.
What is the Atomic Mass?
Average mass of all its naturally occurring isotopes. Measured in Daltons and is usually close to the mass number
What is a Dalton?
A unit for measure the mass of atoms and their subatomic particles
What is an ion?
An atom that is electrically charged because it gives up or gains an electron... have a positive or negative charge
Process of giving up or gaining an electron
What is a molecule?
When 2 or more atoms share electrons
What is included in a molecular formula?
The elements and the number of atoms of each element that make up a molecule (O2... molecule contains 2 atoms of oxygen)
H2O... one oxygen atom shares electrons with 2 hydrogen atoms
What is a compound?
A substance that contains atoms of 2 or more different elements (H2O and NaCl)
What is a Free Radical?
An atoms / group of atoms with an unpaired electron in its outer shell... highly unstable and reactive and destructible to nearby molecules
How does a free radical become stable?
Either by giving up the unpaired electron or by gaining an electron from another molecule
What are some sources of free radicals and what are some illnesses that may be associated with free radicals?
Sources: UV from sun, X-rays, some reactions occur during normal metabolic processes.
Diseases: Cancer, atherosclerosis, Alzheimer's, DM, cataracts, rheumatoid arthritis, aging
Why are antioxidants important?
They inactivate oxygen-derived free radicals. So may slow down aging!
What atoms are most likely to bind with others?
Atoms who do not have a filled valence shell
What is the Octet Rule?
Explains why atoms act in predictable ways. One atom will be more likely to bind with another if doing say will leave both of them with 8 electrons in its valence shell
What are the 3 types of chemical bonds?
Ionic, covalent, and hydrogen
What is an ionic bond?
A force of attraction that holds together 2 ions with opposite charges. Ie Na+ and Cl- create NaCl (sodium chloride). When an atom of sodium donates its sole valence electron to an atom of chlorine the resulting positive and negative charges pull both ions tightly close together and an ionic bond is formed.
What's an electrolyte?
Ionic compound that breaks apart into positive and negative ions in a solution... the solutions conduct a negative current