Learning objectives 2 Flashcards
Essential Basic chemical Concepts
Define and give examples of the following terms using one sentence each: matter (substance), element, atom, compound, and molecule, mixture.
Matter: Matter is any material that has a mass and takes up space.
Element: An element is a substance that cannot be broken down any further.
Atom: An atom is the smallest quantity of an element that retains the unique properties of that element, and it is the building block for a molecule.
Molecule: A molecule is two or more atoms bonded together, and are the building blocks for compounds.
Compound: A compound is two or more molecules chemically bonded together.
Mixture: A mixture is a substance made up of two or more components that can be relatively easily separated using physical means, and that are not chemically bonded together.
In a short paragraph, describe the differences between kinetic and potential energy.
Kinetic energy is the form of energy that matter possess because of its motion.
Potential energy is the energy held by matter because of its position relative to other matter, stresses within itself, its electric charge, or other factors.
Define the following terms using one sentence each and explain how they interact to form an atom: proton, neutron, and electron.
Proton: A proton is a heavy subatomic particle having a positive charge and found in the atom’s nucleus.
Neutron: A neutron is a heavy subatomic particle having no electrical charge and found in the atom’s nucleus.
Electron: An electron is a subatomic particle having a negative charge and nearly no mass, and it’s found orbiting the atom’s nucleus.
Protons and neutrons form the nucleus of an atom and contain most of the atom’s mass, and negatively charged electrons are attracted to orbit around the positively charged nucleus.
In a short paragraph, explain the difference between atomic number and atomic mass, and explain how they are calculated.
The atomic number equals the amount of protons that exist in an atom of an element’s nucleus.
Atomic mass, measured in AMUs (atomic mass units), is the quantity of matter contained in an atom of an element, equating the mass the nucleus.
In a paragraph, describe the relationship between the rule of eights and the number of bonds an atom makes.
The rule of eights, also called the octet rule, states that atoms are most stable when there are exactly eight electrons in their valence shell, or the valence shell is full. Atoms with less than 8 electrons in their valence energy level will tend to seek out electrons in the valence shell of other atoms in order to satisfy the rule of eights. Therefore, an atom will make as many bonds as required to fill their valence energy level.
In a short paragraph, define ions, and describe the relationship between cations and anions, and how hydrogen bonding contributes to their formation in solution. Give an example of a biologically important ion.
Ions are atoms with an overall positive or negative charge. Cations are atoms with an overall positive charge, and anions are atoms with an overall negative charge. When two atoms form an ionic bond, the atoms become charged as electrons in their valence energy shells are donated or accepted between atoms. When an atom donates an electron from its valence shell, it becomes positively charged as the charge of the protons in its nucleus overpower the charge of remaining electrons, therefore becoming a cation. When an atom accepts an electron into its valence energy level from another atom, it becomes negatively charged as the electrons will then outnumber and overpower the positive charge of the nucleus; it becomes an anion. Hydrogen bonds are when a weakly positive hydrogen atom already bonded to one electronegative atom is attracted to another electronegative atom from another molecule. In solution, a negatively charged oxygen atom in a water molecule will attract a positively charged sodium ion (cation), and a positively charged hydrogen in a water molecule will attract a negatively charged chlorine. A biologically important ion is sodium.
In a paragraph, differentiate between the following types of chemical bonds: (a) ionic, (b) covalent, (c) polar covalent and (d) hydrogen. Give an example of each.
An ionic bond occurs when an atom participates in a chemical reaction that results in the donation or acceptance of one or more electrons in the valence energy level of an atom. An example is table salt, NaCl.
A covalent bond occurs when molecules share electrons in their valence shells in a mutually stabilizing relationship, and those electrons move back and forth. An example is oxygen, O2.
A polar covalent bond contains regions with opposite charges, because atoms share electrons unequally. An example of a polar covalent bond is water, H2O.
A hydrogen bond occurs when a weakly positive hydrogen atom already bonded to one electronegative atom is attracted to another electronegative atom from another molecule. An example is water molecules that bond to each other.
Describe in a paragraph how each of the following properties of water is important for human life: solvency, cohesion, adhesion, thermal stability, and chemical reactivity.
Solvency is the tendency of ionic compounds and polar covalent compounds to dissociate into water to create a solution. Water is the universal solvent.
Cohesion is the tendency of water molecules to form hydrogen bonds with other water molecules.
Adhesion is water’s ability to be attracted to polar surfaces.
Thermal stability refers to water’s ability to hold its temperature, because has a very high specific heat capacity due to the collective forces of the many hydrogen bonds.
Chemical reactivity refers to water’s ability to significantly react with other substances when it is added or removed.
Describe in a paragraph the three major types of mixtures: suspensions, colloidal dispersions, and true solutions and give examples of each in the body.
Suspensions are heterogenous mixtures in which particles are visible and do not settle out (are acted on by gravity). They are are translucent, and do scatter light. An example of a suspension in the body is blood.
Colloids are heterogenous mixtures where the particles are not visible to the naked eye, and the particles do not settle out (are not acted on by gravity). The particles are large enough to scatter light, and colloids appear milky or translucent. An example in the body is albumin.
Solutions are homogenous mixtures that have small and invisible particles (solutes) that scatter evenly throughout the solvent. The particles do not scatter light, do not settle out (are not acted on my gravity), and they are transparent. An example is interstitial fluid.
Calculate the molecular weight of a molecule when given its formula.
Calculate the amount of solute and solvent required to make solutions with concentrations presented as a) weight of solute per unit volume, and b) percent solutions.
Define in a paragraph the term mole, and explain how this metric unit relates to the molar concentration of a solution.
In a paragraph, define pH, and differentiate between acids and bases.
In a paragraph, define the term buffer and explain how a buffer works using bicarbonate buffer as your example.
Use simple equations to illustrate, and provide an example of, the following types of reactions: a. decomposition, b. synthesis and c. reversible.
