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bi101 ch 2
vocab and themes
| Question | Answer |
|---|---|
| matter | anything that aces up space and has mass. like a solid liquid or gas. |
| elements | substance that cannot be broken down to simper substances with different properties |
| atoms | smallest part of an element that displays the properties of an element. |
| an atom is made up of | subatomic particles like protons neutrons and electron |
| atomic symbol | one or two letters which stands for name of elements |
| protons are.....neutrons are...electrons are.... | positively charged, neutrally charged, negatively charged |
| what makes up the nucleus | protons and neutrons |
| electron shell | average location of the electrons |
| atomic number | number of protons within the nucleus of an atom |
| mass number | sum of the protons and neutrons in nucleus |
| to get the number of neutrons subtract the protons or atomic number from the | atomic mass number |
| atomic mass | average of amu for all isotopes of electrons |
| isotopes | atoms of the same element that differ in number of neutrons. |
| isotopes have the same number of....but differ in... | protons, atomic masses |
| mass is constant weight changes | according to gravitational pull |
| Who discovered radiation in 1860 | antienne henri becqurel |
| who coined the term radio activity | marie curie |
| tracer | detects molecular changes |
| What does PET stand for | position emission tomography |
| what does a PET scan do? | determines comparative activity of tissue. |
| bohr models of atoms | useful way to visualize electron location. electron shells represent energy levels. |
| octet rule | outermost shell is most stable when it has 8 electrons |
| valence shell | determines whether the atom gives up accepts or shares electron to acquire 8 electrons in the outermost shell |
| molecule | exists when two or more elements bond together and is the smaller part of a compound that retains its chemical properties |
| compound | molecule containing at least two different elements |
| formula | tells you the number of each kind of atom in a molecule |
| ions | particles with net charge of -1 |
| ionic bond | strong attraction between negatively and positively charged ions |
| salts | solid substances that usually separate and exist as individual ions in water |
| covalent bonds | results when two atoms share electron in the outer shell |
| what are the two types of covalent bonds? | polar and nonpolar |
| nonpolar covalent bond | sharing of electrons between two atoms is equal |
| electronegativity | dependent on number of protons. the greater the protons the greater the electronegativity |
| polar covalent bonds | electrons not shared equally (water) |
| hydrogen bond | attraction of a slightly positive hydrogen to a slightly negative atom in the vicinity. |
| two examples of polar covalent bonds: | water and DNA |
| hydrogen bonding is not unique to | water |
| calorie | amount of heat energy needed to raise temperature of 1g of water 1 degree celcius |
| solution | contains dissolved substances |
| solute | dissolved substance in solution |
| hydrophilic | molecules that attract water |
| hydrophobic | molecules that cannot attract water |
| cohesion | ability of water molecules to cling to each other due to hydrogen bonding |
| adhesion | ability of water molecules to cling to other polar surfaces |
| surface tension | force that holds moist membranes together. due to the attraction of water molecules through hydrogen bonding |
| the stronger the force btw molecules in a liquid | the greater the surface tension. water has very high surface tension |
| frozen water is less dense that liquid water. | if ice didn't float ponds, lakes, and rivers would freeze solid, making life impossible. |
| acidic solutions | high in h+ concentrations: lemon juice, vinegar, tomatoes |
| acids | substances that dissociate in water, releasing hydrogen ions |
| basic solutions | low in h+ concentrations: milk of magnesia, ammonia |
| bases | substances that either take up hydrogen ions or regions hydroxide ions. |
| pH scale | used to indicate the acidity or basicity (alkalinity) of solution. |
| what is the system of the pH scale? | ranges from 0(acid) to 14 (base). pH 7 is neutral |
| buffer | chemical (or combination of chemicals) that keeps pH within normal range. |
Created by:
jasmine.teich
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