Elements and Atoms: Building Blocks of Matter Flashcards
Matter
Anything that occupies space and has mass
Weight vs Mass
Mass - amount of matter contained in an object
Weight - an objects mass as affected by the pull of gravity
Element
A type of matter (pure substance) that cannot be created or broken down by ordinary chemical means (Carbon, Sulfur, Hydrogen, Oxygen, Nitrogen)
Compound
A substance composed of two or more (different) elements joined by chemical bonds. The elements that make up any given compound occur in the same relative amounts (ex. Glucose -> C6-H12-O6)
Atom
The smallest possible particle of an element that retains all of the properties of that element
Atomic Number
An atom of carbon is unique to carbon, but a proton of carbon is not. One proton is the same as another, whether it is in carbon, sodium, nitrogen (same for neutrons and electrons). The unique quantity of protons an element contains distinguishes it from other elements. No other element has exactly 6 protons in it’s atoms. Atomic number = number of protons.
Atomic Mass
Protons + Neutrons
Molecule
Two or more atoms chemically combined
Molecular Formula
A combination of symbols that indicates the number and type of atoms in a molecule (ex. H2O)
Structural Formula
Shows the arrangement of atoms/molecules
Valence Shell
An atom’s outermost electron shell. If the valence shell is full, the atom is stable and unlikely to be pulled away from the nucleus by the electrical charge of other atoms. If the valence shell isn’t full, the atom is reactive, meaning it will react with other atoms in ways that make the valence shell full.
Octet Rule
All atoms “want” to have a full outer shell which is 8 electrons (except for hydrogen and helium)
Bond
A weak or strong electrical attraction that holds atoms in the same vicinity
Ion
An atom that has an electrical charge - whether positive or negative.
Atoms typically have the same number of protons as electrons, however when an atom participates in a chemical reaction in order to have a full valence electron shell (octet rule) it’s number of protons and electrons will differ because it either donated or accepted electrons
Cation
A positively charged Ion
Ex. Potassium (K) has atomic number 19, just one electron in it’s valence shell. In chemical reactions it will lose an electron to have a full shell because that is easier than gaining 7. The loss of the negatively charged electron will cause the positively charged protons to be more influential than the remaining negatively charged electrons because there will be more protons than electrons. (K+)
Anion
A negatively charged Ion
Ex. Fluorine, atomic number 9, has 7 electrons in it’s valence shell. It is likely to bond with atoms in such a way that it gains one electron to have a full valence shell (octet rule) because that is easier than losing 7. When it does, it’s electrons will outnumber it’s protons by one, giving it an overall negative charge
Ionic Bond
An ongoing, close association between ions of opposite charge.
The opposite charges of cations and anions exert a moderately strong mutual connection that keeps atoms in close proximity forming an ionic bond. Ex. Sodium commonly donates an electron to chlorine, becoming Na+. When chlorine accepts the electron, it becomes Cl-. With their opposing charges, these two ions strongly attract each other (NaCl).
Electrolytes
Dissolved ions in a liquid state that produce electrical charges within the body
Covalent Bonds
Molecules formed by a covalent bond share electrons in a mutually stabilizing relationship
Electrons move back and forth between the elements. Because of the sharing of pairs of electrons (one electron from each of two atoms) covalent bonds are stronger than ionic bonds
Nonpolar Covalent Bonds
The sharing of the negative electrons between the atoms is relatively equal, as is the electrical pull of the positive protons in the nucleus of the atoms involved. That is why covalently bonded molecules that are electrically balanced in this way are described as non polar, that is, no region of the molecule is either more positive or more negative than any other
Polar Covalent Bonds
A molecule that contains regions that have opposite electrical charges. Polar molecules occur when atoms share electrons unequally.
Ex. Water (H2O) oxygen contains 8 protons and the two hydrogen atoms contain only 1. Because every proton exerts an identical positive charge, the nucleus that has 8 protons exerts a charge eight times greater than a nucleus that contains one proton. This means that the negatively charged electrons present in the water molecule are more strongly attracted to the oxygen nucleus than to the hydrogen nuclei. Each hydrogen atom’s single negative electron therefore migrated toward the oxygen atom, making the oxygen end of their bond slightly more negative than the hydrogen end of their bond
Hydrogen Bond
Formed when a weakly positive hydrogen atom already bonded to one electronegative atom is attracted to another electronegative atom from another molecule. Hydrogen bonds always include hydrogen that is already part of a polar molecule. Not an actual bond, an electrostatic attraction between two solar groups
Inorganic Compounds
A substance that does not contain both carbon and hydrogen
Organic Compound
A substance that contains both carbon and hydrogen
Roles of Water
Lubricant and Cushion - just as oil lubricates the hinge on a door, water in synovial fluid lubricates the actions of body joints, helps the lungs expand and recoil, helps food flow through the digestive tract, endure abdominal organs are friction free
Heat Sink - absorbs the heat generated by chemical reactions without greatly increasing in temperature. Can cool the body by allowing warm blood from the body’s core to flow to the blood vessels under the skin and transfer for it to the environment. Or, sweat glands can release water in sweat, carrying away heat from the body
Component of Liquid Mixtures - works as a “universal solvent”, a water based liquid called a solution. Essentially all of the chemical reactions in the body occur among compounds dissolved in water
Dehydration Synthesis
Forms monomers into polymers. One reactant gives up an atom of hydrogen and another reactant gives up a hydroxyl group (OH) in the synthesis of a new product. In the formation of their covalent bond, a molecule of water is released as a byproduct, and the remaining monomers are left (Joins monomers into polymers).
H——OH H——OH
H——OH-H——OH
^
Forms water
= H H2O OH
Hydrolysis
A molecule of water disrupts a compound, breaking its bonds. The water is itself split into H and OH. One portion of the severed compound then bonds with the hydrogen atom and the other portion bonds with the hydroxyl group
Polymer
A large molecule composed of many repeated subunits
Monomer
Small, simple molecules that are linked with other identical small, simple molecules to form polymers
Macromolecule
Large polymers
Ex. Proteins, lipids, carbohydrates, nucleic acids
Salts
Formed when ions form ionic bonds (two groups of oppositely charged ions). A salt is a substance that when dissolved in water, dissociates into ions.
Acids and Bases
Like salts, dissociate in water into electrolytes. Acids and bases can very much change the properties of the solutions in which they are dissolved
Acid
A substance that releases hydrogen ions in solution. Because an atom of hydrogen has just one proton and one electron, a positively charged hydrogen ions is simply a proton. This solitary proton is highly likely to participate in chemical reactions. Strong acids, like hydrochloric acid, are compounds that release all of their H+ in solution, that is, they ionize completely. Weak acids do not ionize completely, some of their hydrogen ions remain bonded with a compound in solution.
Base
A substance that releases hydroxyl ions (OH-) in solution, or one that absorbs H+ already present in solution. The hydroxyl ions or other base combine with the H+ ions already present to form a water molecule, thereby removing H+ from the solution and reducing its acidity.
pH Scale
Measures relative acidity or alkalinity of a solution, or concentration of H+ (hydrogen ions). For example, a pH solution has a H+ concentration that is ten times greater than that of a pH 5 solutions (ten times more acidic). The lower the number below 7, the more acidic the solution, or the greater the concentration of H+. The higher the number above 7, the more basic (alkaline) the solution, or the lower the concentration of H+
Neutral pH
7 - pure water is pH 7
Buffer
A solution of a weak acid and it’s conjugate base. A buffer can neutralize small amounts of acids or bases in body fluids. Ex. If there is a slight decrease below pH 7.35 in the pH of a bodily fluid, the buffer in the fluid - in this case, acting as a weak base, will bind the excess hydrogen ions. In contrast, if pH rises above 7.45, the buffer will act as a weak acid and contribute hydrogen ions.
Carbohydrate
A molecule composed of carbon, hydrogen, and oxygen. Carbohydrates are referred to as saccharides, a word meaning “sugars”. Three forms are important in the body. Monosaccharides - monomers of carbohydrates. Disaccharides - made up of two monomers. Polysaccharides - polymers
Monosaccharides
Monomers of carbohydrates. Five are important in the body.
“Hexose sugars”
-glucose
-fructose
-galactose
“Pentose sugars”
-ribose
-deoxyribose
Disaccharides
A pair of monosaccharides. Formed via dehydration synthesis. Three are important:
- sucrose
- lactose
- maltose
Polysaccharide
Contain a few to a thousand or more monosaccharides. Three are important:
Starch- polymers of glucose. Plant based foods
Glycogen- polymer of glucose, stored in the tissues of animals (muscles and liver)
Cellulose- cell wall of green plants. Component of plant food referred to as “fiber”
Starch
Polymer of glucose - plants
Glycogen
Polymer of glucose - animals (tissues)
Cellulose
Polysaccharide that is primary component of cell wall in green plants, “fiber”
Functions of Carbohydrates
Energy/fuel - All body cells can use glucose for fuel. Nerve cells and red blood cells can ONLY use glucose for fuel. In the breakdown of glucose for energy, ATP is produced. ATP releases free energy when its phosphate bonds are broken, and thus supplies ready energy to the cells.
Also present in cells. Some carbohydrate molecules bind with proteins to produce glycoproteins, others combine with lipids to produce glycolipids, both of which are found in the membrane that encloses the contents of body cells
Lipids
Fats, oils. Hydrophobic, do not dissolve in water.
Triglyceride
Glycerol (consists of 3 carbon atoms)
\+ (bound by dehydration synthesis)
3 fatty acids
=triglyceride - one of the most common dietary lipid groups
Phospholipid
A bond between the glycerol component of a lipid and a phosphorus molecule.
Recall that triglycerides are nonpolar and hydrophobic. The same holds true for the fatty acid portion of the phospholipid, however the phosphate containing group at the head of the compound is polar and thereby hydrophilic. This is why they are components of the CELL MEMBRANE. They can interact with the watery interior of cells and the watery solution outside of cells.
Also part of BILE
Steroid
Most important: cholesterol
- hormones
- vitamin D
Also used in cell membrane (cholesterol)
Proteins
Organic molecules composed of one or more polypeptides chemically joined.
Peptide Bond- bond between amino acids
Amino Acid
A molecule composed of an amino acid group and a carboxyl group, together with a variable side chain.
20 amino acids contribute to nearly all of the thousands of different proteins important in human structure and function
Peptide Bond
A covalent bond between two amino acids that forms by dehydration synthesis
Dipeptide
Two amino acids chemically joined by a peptide Bond
Tripeptide
Three amino acids chemically joined by a peptide Bond
Polypeptide
Multiple amino acids chemically joined by a peptide bond
Structural Proteins
H20 insoluble Fiberous Proteins
-form structural material
Ex. -Keratin - skin, hair, nails
-collagen - tendons and ligaments, matrix of bone, connected tissue
Functional Proteins
Biochemically active
a. Contractive Proteins (muscles)
b. Messenger molecules (hormones)
c. Immunity Proteins (antibodies)
d. Transport Proteins - transport stuff around the body
e. ENZYMES
Enzyme
A biological catalyst - (a substance that accelerates a chemical reaction without being consumed by the reaction) made of protein
Substrate* - the material upon which an enzyme acts
Hydrolysis
Ex. Starch + H20 ————> glucose
Amylase-enzyme (speeds up this reaction)
Nucleotide
Form energy carrying molecules
- ATP: Adenosin Triphosphate
- ADP: Adenosin Diphosphate
P
- S - B
P: phosphate group
S: 5 carbon sugar
B: organic base
ATP
Holds energy that can be used by the cell
P-P-P
- S - B ——> “charged battery”
ADP
P-P
- S - B —> “dead battery”
Nucleic Acids
DNA + RNA
- genetic material
- protein synthesis
