Terms Sheet 1 - Molecules

Hydrogen bond

Definition: A type of noncovalent chemical attraction created when the partial positive charge of a hydrogen atom is attracted with the partial negative charge of an electronegative atom when covalently bonded together.

Example sentence: The atoms of the element oxygen, nitrogen and fluorine tend to demonstrate strongest examples of hydrogen bonding when chemically bonded with a hydrogen atom.

Covalent bond

Definition: A type of chemical bond where atoms share valence electrons with each other and form electron pairs. This is usually between two nonmetal atoms or one non-metal atom and one metalloid.

Example sentence: Ammonia is an inorganic substance that has covalent bonds between the nitrogen and hydrogen atoms because they each have an odd number of valence electrons.

Polar covalent bond

Definition: A type of covalent bond where there is a difference in charges between the two atoms due to the unequal sharing of electrons. This results in one atom being slightly more negative and the other more positive.

Example sentence: Water molecules have polar covalent bonds between their atoms due to oxygen being more electronegative than hydrogen.

Electronegative

Definition: A characteristic of an atom regarding its electronegativity, which is the amount of attraction a particular atom has for the shared electrons in a covalent bond. An atom which is more electronegative tends to have a stronger pull for the shared electrons to itself.

Example sentence: The most electronegative element is considered to be fluorine while the least electronegative element is cesium.

Kinetic energy

Definition: Energy possessed by any body with mass which is moving, regardless of the direction of its motion and measured in joules (J). The higher the velocity, the higher the kinetic energy of the moving body. 

Example sentence: The formula to calculate kinetic energy is 12mv2, where the kinetic energy of the moving object is directly proportional to its mass, and also directly proportional to the square of the velocity.

Hydrophilic

Hydrophobic

Definition: Water-fearing, meaning that it does not dissolve in water but instead repels it. This can be seen visually with water droplets forming on hydrophobic surfaces.

Example sentence: The phospholipids of the cell membrane have hydrophobic tails, which are sandwiched between the opposing layers of hydrophilic heads.

Dehydration reaction

Definition: A reaction where two molecules are joined together into one molecule through the loss of water.

Example sentence: Peptides create proteins through dehydration synthesis, with the amino group of one peptide reacting with the carboxyl group of the other peptide.

Hydrolysis

Definition: A process in which a water molecule is inserted into the bond between monomers and breaks polymers apart.

Example sentence: Human digestion works by using hydrolysis to break down polymers so that they can be used for specific functions within cells.

Macromolecules

Definition: A large chemical structure of multiple atoms bonded together.

Example sentence: Carbohydrates, a long chain of carbons bonded with Oxygen and hydrogen are a common macracromolecule.

Polymer

Definition: A large molecule of repeating monomers linked by covalent bonds.

Example sentence: Cellolose is a common polymer found in cell walls that consists of repeating glucose molecules.

Monomer

Definition: A small molecule that combines with others like it to form polymers.

Example sentence: Glucose is a common monomer consisting of carbon, hydrogen, and oxygen.

Carbohydrates

Definition: A macromolecule that makes up sugars and polymers of sugar.

Example sentence: Starch and glycogen are both polymers of glucose, which is a simple carbohydrate.

Lipids

Definition: A lot of the time not considered macromolecules for their size, and they do not have true polymers. Lipids are hydrophobic and have various forms and functions.

Example sentence: Fats are a type of lipid, and they can be unsaturated or saturated, depending on the amount of double bonds within the structure.

Proteins

Nucleic Acids