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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.

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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.

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