Exam 1 study guide Flashcards
The scientific method steps
observations, hypothesis formation, experimentation, data analysis, conclusion
non-polar covalent bonds
atoms with similar electronegativities. Electrons shared equally
-covalent bonds are the strongest bc the atoms thing that the electron shared is theirs so they work hard to keep it
polar covalent bonds
atoms with different electronegativities, pos and neg. Shared unequally Ex:water
Electronegativity – what is it? Why is it significant? How does it relate to bond formation?
Def: ability of nucleus to attract electrons
Electronegativity is significant because
-It explains the stability of chemical compounds.
-It predicts the type of bond (covalent or ionic)
-It makes bonding between atoms possible
Ionic bonds
Ionic bond: is an attraction of positive and negative: definition for test
Electrons transferred, forming ions that are attracted to each other
-positive ion being attracted to negative ion
-ions are atom or molecule with charge
-Cation: pos charge, lost electrons
-Anion: neg charge, gained electrons
-Ionic bond: cation binds to an anion like i said pos being attracted to neg
Hydrogen bonds
Hydrogen bonds:
Electropositive hydrogen from one polar molecule is attracted to an electronegative atom
-water molecules form multiple hydrogen bonds with each other
van der Waals interactions
Van der Waals forces are weak intermolecular forces that are dependent on the distance between atoms or molecules. These forces arise from the interactions between uncharged atoms/molecules.
For example, Van der Waals forces can arise from the fluctuation in the polarizations of two particles that are close to each other.
4 “big picture” properties of water
high specific heat, hydrogen bonding alters the state of water, (cohesion, adhesion, surface tension), -ions and polar molecules dissolve readily in water, hydrophilic, hydrophobic interactions
Cohesion/adhesion
cohesion: (kindergarteners hold each others hands) water molecules are attracted to other water molecules and stick together via hydrogen bonding.
Adhesion: (kindergarteners holding teachers hand) water molecules are attracted to something that is not water (other polar molecules) and stick via hydrogen bonding
surface tension
Surface tension: measure of attraction between molecules at the surface of a liquid (LEARN MORE)
Moderation of temperature by water
Water moderates temperature in the following ways:
Water has a high specific heat, meaning it can absorb a lot of heat before its temperature rises.
Liquid water at the surface takes longer to heat up and cool down compared to air, helping to stabilize temperature.
Coastal areas near bodies of water have more moderate temperatures due to water’s high heat capacity.
Expansion upon freezing
Water expands upon freezing due to the following reasons:
Molecules set themselves in a very open arrangement that contains more space than the water in the liquid state.
Bodies of water freeze on the top first due to the maximum density of water at about 4°C.
Hydration shell
When the solvent is water, it is called a hydration shell or hydration sphere. The hydration shell represents water’s attraction or adhesion to a substance, and the greater the attraction, the greater the number of water molecules involved in the hydration shell.
hydrophobic vs hydrophilic
Hydrophilic: water loving, things that can dissolve in water, often have a charge like polar or ionic. Hydrophobic: water fearing, do not like water, nonpolar, no charge. Amphipathic have hydrophilic and hydrophobic regions, they form micelles when placed into water
Define acid/base and understand the pH scale and what it means in terms of H+ content
As Acidity goes up, pH goes down, H+ donor
Base (akline) when put in water the pH goes higher, H+ acceptors
The term “base” in pH refers to:
A substance that accepts hydrogen ions.
When dissolved in water, it results in a solution with more hydroxide ions than hydrogen ions, making it alkaline.
On the pH scale, values greater than 7 are considered basic.
Buffers- what they do and the example of the buffer system in blood
Buffers: pair of substances that minimize Ph fluctuations in the fluids of living organisms
Most buffers consist of a weak acid and a weak base. They help maintain a given pH even after the addition of an acid or a base. For example, blood contains a carbonic acid (H 2 CO 3)-bicarbonate (HCO 3-) buffer system. In this system, the weak acid dissociates to a small extent, giving bicarbonate ions
Dehydration synthesis & hydrolysis reactions
Hydrolysis reactions: a chemical reaction that breaks apart molecules using water
Dehydration reaction or dehydration synthesis reaction is a chemical reaction in which two molecules join together via a covalent bond, with the removal of a water molecule. . A dehydration reaction is a specific type of condensation reaction and synthesis reaction.
functional groups examples
carboxyl: carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (–OH), giving it the formula R-COOH where “R” represents the rest of the molecule
hydroxyl: hydroxyl group (―OH), in chemistry, a functional group with one hydrogen and one oxygen atom.
Carbohydrates
Carbohydrates: sugars, usually long chains
-composed of C,H, and O atoms (carbon with water)
Monosaccharides
Monosaccharides: simplest sugar
e.g. glucose, fructose, ribose
Disaccharides
Carbohydrates composed of 2 monosaccharides
e.g. sucrose
Polysaccharides
many monosaccharides
e.g. glycogen, starch, cellulose, chitin
Lipids: know the 3 classes of lipids
(fats, phospholipids, steroids)
Unsaturated fatty acids
-describe bonding
Unsaturated fatty acids: 2 or more carbons in the fatty acid contain a double bond, each double bond forms a kink, forms a tail, lower melting point, liquid at room temp like oils, found in plants
