college biology

Elements

Substances that cannot be broken down any further, made of atoms.

Give an example that illustrates how a molecule's shape can determine its biological function.

A molecule's characteristic size and shape affect how it interacts with other molecules. When atoms form covalent bonds, their s and three p orbitals hybridize to form four teardrop-shaped orbitals in a tetrahedral arrangement. These hybrid orbitals dictate the specific shapes of different molecules.

Energy

Ability to do work

Distinguish between an element and a compound

An element is made up of atoms, whereas a compound is made up of two or more elements with a fixed ratio.

Essential elements:

Any element required by an organism for healthy growth and stability. Examples are Oxygen, Hydrogen, Carbon, and Nitrogen

Matter

Anything that has mass and takes up space

atomic number vs mass number

Atomic number describes how many protons are in the atom, whereas the mass number describes the sum of protons and neutrons in that atom.

atomic weight vs mass number

Atomic weight how many grams are in one mole of an element, whereas the mass number is the sum of protons and neutrons in the atom.

Atoms and Molecules

Atoms are the most basic unit of matter, molecules are compounds made up of two or more atoms.

Isotopes

Atoms with the same number of protons, but a different number of neutrons.

Nucleus

Center of the atom, where the proton and neutron reside

Explain what is meant by a chemical equilibrium.

Chemical equilibrium is reached when the forward and reverse reactions proceed at the same rate, and the relative concentrations of reactants and products no longer change.

Chemical reactions

Convert reactants to products. Reaction between two or more chemicals.

Trace elements

Elements required by the human body in very minute amounts.

Distinguish between hydrogen bonds and van der Waals interactions.

Hydrogen bonds is a type of van der Waal force that is an atom covalently bonded with an electronegative atom, and thus has a partial positive charge, it can be attracted to another electronegative atom. Van der Waal interactions are attracted to each other when in close contact.

Atomic number

Indicates the number of protons in the element.

Mass number

Indicates the sum of protons and neutrons in the element.

Explain how two isotopes of an element are similar. Explain how they are different

Isotopes are similar because they all have the same number of protons, they are different because they all have a different number of neutrons.

Anion

Negative ions

Distinguish among nonpolar covalent, polar covalent and ionic bonds.

Nonpolar covalent bonds: If the atoms in a molecule have similar electron egatives, the electrons remain equally shared between the two nuclei, and the covalent bond. Polar covalent bonds: If one element is more electron negative, it pulls the shared electrons closer to itself. Ionic bonds: Holds cation and anion ions together because of their opposite attraction.

Energy of shells (inner/outer)

Outer shells have more energy, inner shells have less

Cation

Positive ions

Explain why strong covalent bonds and weak bonds are both essential in living organisms.

Strong Covalent bonds link atoms to form a cell's molecules. Weak bonds can be broken down and can be made again easily.

Compounds

Substances consisting of two or more elements with a fixed ratio. Can be broken down into different atoms and elements.

Periodic table

Table of atomic elements arranged in a specific order.

Electron shells (stability)

The closer to the nucleus a shell is, the stable it becomes.

Identify the four elements that make up 96% of living matter.

The four elements are Carbon, Hydrogen, Oxygen, and Nitrogen.

neutron vs proton

The neutron has no charge at all, whereas the proton has a positive charge. Neutron is slightly larger than a proton as well.

Electronegativity

The strength of an element to pull electrons toward itself.

Elements required by organisms

These are known as essential elements. Examples include Carbon, Nitrogen, Oxygen, and Hydrogen.

Describe two biological applications that use radioactive isotopes.

They can be used to treat cancer, they can act as medical tracers, and they can also help date fossils.

Define the term trace element and give an example

Trace elements are elements that organisms only need in minute quantities. Example: Iron

Equilibrium

When the forward and reverse reactions are at the same rate, the reaction is over.

Chemical bonds (covalent, ionic)

When two elements share a pair of valence electrons. Ionic bonds are bonds between ions, one of the ions in the bond strips electrons away from the other.