Term
|
Definition
| anything that takes up space and has mass |
|
|
Term
|
Definition
| basic substances that cannot be broken down to substances with different properties; composed of only one type of atom |
|
|
Term
|
Definition
tiny particles;
smallest particle of an element that displays the properties of the element
page 20 |
|
|
Term
|
Definition
| One or two letters create this symbol, which stands for it's name |
|
|
Term
|
Definition
| mass number of an atom is just about equal to the sum of its protons and neutrons |
|
|
Term
|
Definition
located within the nucleus of an atom
proton: positive subatomic particle located in the nucleus and assigned one atomic mass unit
neutrons:
neutral subatomic particle located in the nucleus and assigned one atomic mass unit |
|
|
Term
|
Definition
| subatomic particle that moves about the nucleus |
|
|
Term
|
Definition
| all atoms of an element have the same number of protons. This is the atom's atomic number. |
|
|
Term
|
Definition
| atoms of the same element that differ in the number of neutrons. They have the same number of protons, but have different mass numbers. |
|
|
Term
|
Definition
| substance having an attached radioactive isotope that allows a researcher to track its whereabouts in a biological system. |
|
|
Term
|
Definition
particular volume of space where an electron is most apt to be found most of the time
Orbitals near the nucleus are circular or dumbbell shaped. Other shapes occur in more distant orbitals.
Orbitals contain no more than two electrons |
|
|
Term
|
Definition
| states than an atom other than hydrogen tends to form bonds until it has eight electrons in its outer shell; an atom that already has eight electrons in its outer shell does not react and is inert. |
|
|
Term
|
Definition
| when atoms of two or more different elements bond together, the product is called a compound. |
|
|
Term
|
Definition
| smallest part of a compound that still has the properties of the compound. |
|
|
Term
|
Definition
| Ionic compounds are held together by an attraction between negatively and positively charged ions called an ionic bond. |
|
|
Term
|
Definition
| sodium chloride is an ionic compound formed when sodium reacts with chlorine |
|
|
Term
|
Definition
chemical bond in which atoms share one pair of electrons
results when two atoms share electrons in such a way that each atom has an octet of electrons in the outer shell (or two electrons in the case of hydrogen) |
|
|
Term
|
Definition
| when the sharing of electrons between two atoms is fairly equal. |
|
|
Term
|
Definition
the attraction of an atom for the electrons in a covalent bond.
oxygen atom is more electronegative than the hydrogen atom, so the oxygen atom can attract the electron pair to a greater extent than each hydrogen atom can. |
|
|
Term
|
Definition
bond in which sharing of electrons between atoms is unequal.
in the case of water, the molecule itself is a polar molecule. |
|
|
Term
|
Definition
polarity within a water molecule causes the hydrogen atoms in one molecule to be attracted to the oxygen atoms in other water molecules. this attraction, although weaker than ionic or covalent bonds, is called a hydrogen bond.
because it is easily broken, it is often represented by a dotted line |
|
|
Term
|
Definition
| when ions and molecules disperse in water, they move about and collide, allowing reactions to occur. those molecules that can attract water are said to be hydrophilic |
|
|
Term
|
Definition
| nonionized and nonpolar molecules that cannot attract water |
|
|
Term
|
Definition
| contains dissolved substances, called solutes |
|
|
Term
|
Definition
|
|
Term
|
Definition
| substances that dissociate in water, releasing hydrogen ions (H+) |
|
|
Term
|
Definition
| substances that either take up hydrogen ions (H+) or release hyroxide ions (OH-) |
|
|
Term
|
Definition
used to indicate the acidity and basicity (alkalinity) of a solution.
pH of 7 is neutral |
|
|
Term
|
Definition
| help keep the pH within normal limits because they are chemicals or combinations of chemicals that take up excess hydrogen ions (H+) or hydroxide ions (OH-) |
|
|
