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23 Cards in this Set
- Front
- Back
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What is an element? How many elements naturally occur in the Universe? How many are used by life forms on Earth?
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A substance that cannot be broken down to other substances by chemical reactions and still maintain it's physical and chemical properties.
There are 92 naturally occurring elements 25 of the 92 are essential to living organisms on Earth |
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What is a compound? Is O2 a compound? If not, what is it?
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A substance consisting of two or more elements in a fixed ratio.
A compoind has characteristics different from those of its elements. O2 is not a compound. It is a molecule containing 2 oxygen atoms. NOTE TO SELF: Ask if the final part to this is correct. |
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What are the four most common elements (by weight) in the human body?
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Oxygen (65%), Carbon (18.5%), Hydrogen (9.5%) and nitrogen (3.3%)
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There is lots silicon (Si) on Earth but life forms don’t use this element, even though it can form 4 bonds with other molecules, just like carbon. Why is this?
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NOTE TO SELF: Ask
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What happens when a person has an iodine deficiency?
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They get Goiter
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Upon what does an element’s chemical behavior and properties depend?
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the structure of the atom
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What are the three main “parts” of an atom? Where is each located?
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Proton (inside nucleus), neutron (inside nucleus) and electrons (various energy shells around the nucleus)
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Be able to define atomic number, mass number, and atomic mass.
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Atomic number is the number of protons an atom has
Mass number is the sum of the protons and neutrons in an atom Atomic mass is the atom's total mass which can be approximated by the mass number |
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What are isotopes? Are all isotopes radioactive? Be able to give examples.
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Isotopes are two atoms of an element that differ in the number of neutrons
Radioactive isotopes decay spontaneously, giving off particles and energy |
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How are radioactive isotopes used to date rocks?
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Comparing the ratios of the isotopes of carbon present
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Where does an atom store its energy? (E = mc2)
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Part of it is stored in it's nucleus and part of it is stored in the energy levels of its electrons.
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What is an electron shell? Does an electron have more energy when it’s in an outer shell or an inner shell?
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An electrons state of potential energy is called its energy level, or electron shell.
Outer |
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When an electron changes shells and loses energy, in what form does it release the energy?
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Photons
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How can radioactive isotopes be used to detect cancerous tissue in a PET scan?
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dunno
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How could you use radioactive isotopes to determine the optimal pH for DNA polymerase (the enzyme that replicates DNA)?
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dunno
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What are valence electrons?
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Valence electrons are electrons in the outer most shell.
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Given the atomic number of an element, be able to draw out its shells and the locations of the electrons in its shells.
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The number indicates the shell, and the letter indicates the orbital.
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Be able to predict whether an element is likely to form a bond with another element and what type of bond (covalent or ionic) it will form.
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based on valence electrons
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What is the difference between an electron shell and an electron orbital?
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An electron shell can have many orbitals
An electron shell is the energy levels of electrons around the nucleus. Electron orbitals are where the electrons are likely to be found 90% of the time. |
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How many orbitals are in the first shell? How many are in the second shell? The third shell?
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The first shell can have 1 orbital which can hold 2 electrons.
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What is a covalent bond? What is an ionic bond?
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A covalent bond is one in which electrons are shared between two molecules.
An ionic bond is where one molecule gives up electrons and the other gains electrons. |
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What is electronegativity? How does the greater electronegativity of oxygen over hydrogen affect the behavior of water molecules?
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Electronegativity is the ability of an atom to attract electrons toward itself.
The greater electronegativity of oxygen means that the electron shared in the covalent bond between H & O will spend more of it's time near the oxygen. This causes the entire molecule to be polarized. |
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What is a hydrogen bond? Is this type of bond strong or weak?
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Weak
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