Chemistry and Water Flashcards
how many elements did chemists recognize?
92
how many essential elements do we have?
25
what are essential elements?
elements needed to be healthy and reproduce
what are the elements called that are required by an organism in minute quantities?
trace elements
what element is needed to maintain the thyroid gland?
I
what element is a component of hemoglobin?
Fe
what element prevents tooth enamel from being attacked by bacteria?
Fl
what is and what can hypothyroidism lead to?
iodine deficiency; goiter
what royal queen of France had a goiter in the 1600s?
Marie de Médicis (wife of Henry IV)
how much would it cost to purchase the elements to make an adult human?
$118.63
what is an example of a naturally occurring element that is toxic to organisms?
arsenic can cause cancers
what are isotopes?
have more neutrons than other atoms of the same element and hence, a greater mass
what is an unstable carbon isotope?
C-14 in that the nucleus decays spontaneously giving off particles and energy as it decays into N-14; beta decay
half life of C-14?
5,730 years
what are isotopes used for? (2)
determine age of fossils through radioactive tracers
treat cancer through radioactive therapy
another use of radioactive tracers?
spies for medical diagnosis- test for GERD (gastroesophageal reflux disease) in newborns who spit up they drink radioactive barium Ba)
what type of energy do electrons have? based on what?
potential energy based on their position relative to the nucleus of an atom
relationship between potential energy of an electrons and its position relative to the nucleus?
electrons near the nucleus have low potential energy by can be excited to a higher energy level as they gain energy
what happens when an electron returns to a lower level?
energy is lost in the form of light or heat
how to plants use the energy released from electrons?
harness the energy to produce C6H12O6
where on the staircase does the ball have the greatest potential energy?
top of the staircase
sunlight strikes the surface of a car exciting the electrons to higher energy levels. When they fall back to their original levels what happens?
the car surface feels hot
what happens when you bite into a Wint-O-Green Lifesaver in the dark?
produces a faint blue light
types of chemical bonding? (2)
valence electrons participate in molecule and compound bonding