Color coded: Biochemistry - Chemistry Basics
Atom:the smallest unit of an element that maintains the chemical properties of the element
Subatomic Particles
Proton:Subatomic particles that carry a positive charge.
Located in the nucleus of an atom.
The number of protons never changes in an element.
The number of protons determines the identity of the element and defines the atomic number of the element.
Example: The atomic number for gold is 79 because it has 79 protons.
Neutron:Subatomic particles that carry NO charge (are neutral).
Located in the nucleus of an atom.
Similar in size to a proton.
The number of neutrons can change.
Isotopes:Atoms of the same element with different numbers of neutrons.
Example: Carbon occurs naturally in three isotopes: carbon 12 has 6 neutrons, carbon 13 has 7 neutrons, and carbon 14 has 8 neutrons, but they all have 6 protons.
Electrons:Subatomic particles that carry a negative charge.
Located in the “Electron Cloud”.
The electrons are attached to positive protons in the nucleus, but can move within the electron cloud.
The number of electrons associated with an atom can change.
Ions:Atoms with different numbers of electrons than the normal amount for that elements and are charged.
Example: Lithium (Li) as a neutral atom has 3 protons, 3 neutrons, and 3 electrons. Li- carries a negative electrical charge and has 3 protons, 3 neutrons, and 4 electrons. Li+ carries a positive electrical charge and has 3 protons, 3 neutrons, and 2 electrons.
Molecule:Two or more atoms that are covalently bonded together.
Example: A water molecule has 2 covalent bonds connecting the 2 hydrogen atoms to the 1 oxygen atom.
E levels/ E - Shells:Where the electrons are located within an atom or molecule.
Adding energy to the electrons make them move father out, away from the nucleus.
Losing energy causes them to move inward, toward the nucleus.
Valence Shell:Where the outer most electrons are located on an atom.
Valence E:Refers to the outer most electrons.
These are the most important for chemical bonds and the chemical properties of an element or molecule.
Most elements need 8 valence electrons (an octet) in order to be chemically stable.
Atoms react with other elements in order to obtain a total of 8 valence electrons and to become chemically stable.
Chemical Bonds (These occur between atoms.)
Covalent Bonds:A type of intramolecular bond resulting from the sharing of valence electrons between atoms.
Polar molecules:A molecule in which one end of the molecule is slightly positive, while the other end is slightly negative.
Example: Water is a polar molecule because the 2 hydrogens carry a slightly positive charge while the 1 oxygen carries a slightly negative charge.
Non-polar molecules:A molecule in which both atoms share equal charges.
Electronegativity:Refers to an atom’s desire to acquire electrons.
Hydrogen is the least electronegative atom.
Oxygen and Nitrogen are the most biologically important molecules with a high electronegativity.
Molecules which contain oxygen and nitrogen are likely to be polar.
Ionic bonds:Bonds formed between metal and non-metal atoms
They form when the metal atom loses electrons and the non-metal atom gains electrons.
Both atoms do this in order to have 8 valence electrons.
Salts:Compounds held together by ionic bonds.
Ionic bonds are very strong when the compound is dry.
Ionic bonds are easily broken in water.
Cations:Ions which possess a positive charge because they have more protons than electrons. The metal atoms in a salt typically become cations.
Anions:Ions which possess a negative charge because they have more electrons than protons. The non-metal atoms in a salt typically become anions.
Hydrogen bonds:Weak chemical bonds that form when a hydrogen atom that is covalently bonded to one.
Hydrogen bonds are often depicted as dots in chemical diagrams.
Hydrogen bonding is very important in water due to its polar nature.
Hydrogen bonding aids in cohesion, adhesion, surface tension, high heat capacity, and expansion upon freezing.
Atom:the smallest unit of an element that maintains the chemical properties of the element
Subatomic Particles
Proton:Subatomic particles that carry a positive charge.
Located in the nucleus of an atom.
The number of protons never changes in an element.
The number of protons determines the identity of the element and defines the atomic number of the element.
Example: The atomic number for gold is 79 because it has 79 protons.
Neutron:Subatomic particles that carry NO charge (are neutral).
Located in the nucleus of an atom.
Similar in size to a proton.
The number of neutrons can change.
Isotopes:Atoms of the same element with different numbers of neutrons.
Example: Carbon occurs naturally in three isotopes: carbon 12 has 6 neutrons, carbon 13 has 7 neutrons, and carbon 14 has 8 neutrons, but they all have 6 protons.
Electrons:Subatomic particles that carry a negative charge.
Located in the “Electron Cloud”.
The electrons are attached to positive protons in the nucleus, but can move within the electron cloud.
The number of electrons associated with an atom can change.
Ions:Atoms with different numbers of electrons than the normal amount for that elements and are charged.
Example: Lithium (Li) as a neutral atom has 3 protons, 3 neutrons, and 3 electrons. Li- carries a negative electrical charge and has 3 protons, 3 neutrons, and 4 electrons. Li+ carries a positive electrical charge and has 3 protons, 3 neutrons, and 2 electrons.
Molecule:Two or more atoms that are covalently bonded together.
Example: A water molecule has 2 covalent bonds connecting the 2 hydrogen atoms to the 1 oxygen atom.
E levels/ E - Shells:Where the electrons are located within an atom or molecule.
Adding energy to the electrons make them move father out, away from the nucleus.
Losing energy causes them to move inward, toward the nucleus.
Valence Shell:Where the outer most electrons are located on an atom.
Valence E:Refers to the outer most electrons.
These are the most important for chemical bonds and the chemical properties of an element or molecule.
Most elements need 8 valence electrons (an octet) in order to be chemically stable.
Atoms react with other elements in order to obtain a total of 8 valence electrons and to become chemically stable.
Chemical Bonds (These occur between atoms.)
Covalent Bonds:A type of intramolecular bond resulting from the sharing of valence electrons between atoms.
Polar molecules:A molecule in which one end of the molecule is slightly positive, while the other end is slightly negative.
Example: Water is a polar molecule because the 2 hydrogens carry a slightly positive charge while the 1 oxygen carries a slightly negative charge.
Non-polar molecules:A molecule in which both atoms share equal charges.
Electronegativity:Refers to an atom’s desire to acquire electrons.
Hydrogen is the least electronegative atom.
Oxygen and Nitrogen are the most biologically important molecules with a high electronegativity.
Molecules which contain oxygen and nitrogen are likely to be polar.
Ionic bonds:Bonds formed between metal and non-metal atoms
They form when the metal atom loses electrons and the non-metal atom gains electrons.
Both atoms do this in order to have 8 valence electrons.
Salts:Compounds held together by ionic bonds.
Ionic bonds are very strong when the compound is dry.
Ionic bonds are easily broken in water.
Cations:Ions which possess a positive charge because they have more protons than electrons. The metal atoms in a salt typically become cations.
Anions:Ions which possess a negative charge because they have more electrons than protons. The non-metal atoms in a salt typically become anions.
Hydrogen bonds:Weak chemical bonds that form when a hydrogen atom that is covalently bonded to one.
Hydrogen bonds are often depicted as dots in chemical diagrams.
Hydrogen bonding is very important in water due to its polar nature.
Hydrogen bonding aids in cohesion, adhesion, surface tension, high heat capacity, and expansion upon freezing.
