chemistry

Question 1

what 4 elements make up 96% of organisms?

Answer 1

C, H, O, N

Question 2

other important elements?

Answer 2

Ca, P, K, Na, Cl, Mg, Fe, I, Zn

Question 3

Bohr’ diagram

Answer 3

includes all protons, neutrons, and rings for all electrons

Question 4

lewis structure

Answer 4

valence electrons represented as dots around the letter of the element

Question 5

isotopes

Answer 5

of neutrons varies from protons and electrons. in nature, elements occur as a mixture of its isotopes

Question 6

radioactive isotopes

Answer 6

nucleus decays releases gamma, beta, alpha particles and energy. sometimes so much is released that protons are lost changing the element

Question 7

half life

Answer 7

time required for 1/2 of the atoms of the radioactive isotopes to decay

Question 8

half life of C 14

Answer 8

5760 yrs

Question 9

carbon dating

Answer 9

plants fix C14 during photosynthesis that matches level of isotope in the atmosphere. compare C14 in the fossil to the C14 expected in the atmosphere of the time

Question 10

other uses for radioactive isotopes in organisms

Answer 10

chemotherapy, trace carbon through processes, diagnostic imaging

Question 11

energy and electrons

Answer 11

the further away an e- is from the nucleus the more potential energy it has

Question 12

covalent bond

Answer 12

atoms share e-, strong, backbone of macromolecules

Question 13

electronegativity

Answer 13

atoms within a molecule attract shared e- to a varying degree depending on the element

Question 14

ionic bonds

Answer 14

electronegativity can strip e- from another atom. what atoms gain/lose an electron, ions are produced which are very unstable. the actual bonds created are attractions between opposite charges

Question 15

hydrogen bonds

Answer 15

weak, often due to polarity

Question 16

Van der Waals forces

Answer 16

2 molecules being temporarily attracted to each other d/t charges created by moving e-. 1 is weak but many is strong. protein shape and geckos climbing walls