| A | B |
|---|
| Matter | Matter – anything that has weight and takes up space. Includes solids, liquids, and gases |
| What elements make up more than 95% of the human body? | oxygen, carbon, hydrogen and nitrogen make up more than 95% of the human body. |
| What are atoms? | Elements are composed of tiny particles called atoms. Atoms are the smallest complete units of elements |
| Describe the atom's make-up. Include locations and charges. | Protons (+) and neutrons (neutral) are found on the atom’s nucleus, while electrons (-) circle the nucleus. |
| Atomic number - | # of protonsAtoms with the same atomic number belong to the same element, and thus have the same inherent properties. |
| Mass | refers to the amount of a substance |
| Weight | refers to the force exerted on a substance by gravity |
| Atomic mass | - of an atom refers to the sum of the masses of protons and neutrons. |
| Isotopes | - Atoms of an element that possess a different number of neutrons. Have the same atomic # b/c # of protons stays the same |
| Orbital | refers to the area around a nucleus where an electron is most likely found. Chemical behavior of an atom is determined by the number and arrangement of its orbitals. Electrons can absorb energy and release energy |
| Ions | - Atoms in which the number of protons and electrons differ. |
| Cation - | - Contains more protons than electrons, and carries a positive charge. |
| Anion - | Contains fewer protons than electrons, and carries a negative charge |
| Oxidation - During chemical reactions | loss of an electron |
| Reduction - During chemical reactions | gain of an electron |
| Dmitri Mendeleev | invented periodic table |
| Octet rule | Most atoms important to life can contain no more than 8 electrons |
| molecule | refers to a group of atoms held together by energy in a stable association. O2 example. Note it's only one type of atom-- oxygen |
| Compound | is composed of two or more different types of atoms bond together. NaCl note--2 atoms groups sodium and cloride |
| Atoms in a molecule are joined by _________ | chemical bonds. |
| Ionic bonds | -are formed because ions of opposite charge attract one another. table salt ** Sodium Na+ Chlorine Cl- |
| Covalent bonds | -- are formed when two or more atoms share pairs of valence electrons.--Remember co as in cohabit means to share a space. co-share valent-valence electrons |
| Covalent bond strength-- | Strength depends on number of shared electrons. Share one = single bond, share two = double bond = share three = triple bond |
| hydrogen bonds- | is a chemical bond between the hydrogen atom and an electronegative atom. An example of hydrogen bond is water molecules bonding together in the form of ice. |
