1. Given that most of the elements on the periodic table don’t show up in living cells to
any significant degree, where on Earth are they found? Pick three elements, do a little
Internet research and find out where they are commonly found.
– Majority are found on Earth, but most are found in small quantities. Oxygen and
Silicon are found in the ground, because rocks are made mainly of silicon dioxide.
Earth’s core is made mostly of iron. In the ocean the is mainly sodium and chlorine in
smalls amounts in seawater.
2. C, H, O, and N make up the bulk of the atoms in the human body. However, there are
many trace elements present as well. Pick three of these trace elements and do a little
Internet research to find out where they’re found and what they’re used for in the body.
– Hydrogen and oxygen make water that is made of 75% of your body. The air is
nearly 99% of nitrogen and oxygen, with less than 1% of carbon dioxide.
7. Why do atoms in the same group on the periodic table act similar chemically to one
another?
– Its by chemical properties and the similarities in the number of protons, masses,
spectral lines, and abundances.
12. When a covalent bond forms, atoms add additional electrons to their valence.
However, their charges do not become unbalanced. Why not?
– A covalent bond is shared only by electron between the two atoms. When the
negative and positive charges attract only their nucleus, the electrons will spend more
time the two nuclei balancing it out.
14. What holds the atoms together in a covalently bonded pair?
– The attraction, of positive and negatively charged shared electrons is greater then the charges