Chapter 2 Flashcards
The Chemical Foundation of Life
What is matter?
Anything that has mass and takes up space. Forms of energy are not matter. (heat, sound, electricity).
You cannot have matter without…
Energy
Define the law of conservation of matter
Matter cannot be created or destroyed; it is a cycle
Element
A substance that cannot be broken down into simpler substances by ordinary chemical reactions.
What four elements make up more than 96% of the mass of most organisms? (CHONP)
Carbon, hydrogen, oxygen, nitrogen, and phosphorus.
What is an atom?
The smallest unit of an element that retains the chemical properties of an element.
What are atoms made up of?
Protons, neutrons, electrons
What is electron configuration?
The electron configuration of an atom describes the distribution of electrons in the atom’s orbitals.
How do you determine the atomic mass? (AMU)
Add the number of protons and neutrons together.
Why might an element try to bond?
To complete its valance shell, it either gains or loses electrons
What is an ion?
An electrically charged atom where the number of protons and electrons differ.
What is an isotope?
An atom of the same element differing in number of neutrons. (Carbon-12 6p, 6n and Carbon-14 6p, 8n)
What does a chemical compound consist of?
Atoms of two or more elements combined in a fixed ratio, such as NaCl(table salt), CH4(methane), and NaHCO3 (baking soda).
What determines a molecule?
Two or more atoms joined very strongly, such as H20 (water) and C6H12O6 (glucose).
What is the valence shell, and what does it determine
It is the outermost concentric ring in a Bohr Model, and it determines how an atom will react with other atoms.
What are covalent bonds?
Covalent bonds are like two atoms holding hands by sharing their electrons. The electrons act as the “hands” that keep the atoms connected, allowing them to stay bonded together.
What are non-polar covalent bonds?
When covalently bonded atoms have similar electronegativities, electrons are shared equally
What is a polar covalent bond, and what does it result in?
A polar covalent bond is a chemical bond where electrons are shared unequally between two atoms. This results in one atom having a partial negative charge and the other a partial positive charge.
What types of bonds are there
Single, double, or triple bond.
Electronegativity
A measure of how strongly an atom attracts electrons when it forms a bond with another atom. In simple terms, it tells us how much an atom “wants” electrons when it’s sharing them with another atom.
What is a cation and how are they formed?
A cation is an atom that has lost one or more electrons, resulting in a positive charge.
Formation: Atoms with 1, 2, or 3 valence electrons tend to lose those electrons to achieve a stable electron configuration, becoming positively charged.
What is an anion, and how does it form?
An anion is an atom that has gained one or more electrons, resulting in a negative charge.
Formation: Atoms with 5, 6, or 7 valence electrons tend to gain additional electrons to fill their outer shell, becoming negatively charged.
How do ionic bonds form?
By the attraction between the positive charge of a cation and the negative charge of an anion. (sharing valence electrons to bond)
What happens when ionic compounds are placed in water?
They tend to dissociate into individual ions. NaCl (in H2O) -> Na+ + Cl-
What is a solvent? Example?
A solution capable of dissolving many substances. Water, hydrofluoric acid (JESSE WE HAVE TO DESTROY THE BODY)
What is a solute?
A substance that has been dissolved.
Why does water allow polar substances to dissolve in it?
Because water is a polar molecule, meaning it has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. Non-polar molecules have no charge.
What are hydrogen bonds, and how do they form?
Hydrogen bonds form between the partial positive charge (hydrogen), and the partial negative charge (oxygen) of a neighboring water molecule.
How many hydrogen bonds can each water molecule form with neighboring water molecules?
Each water molecule can form hydrogen bonds with up to 4 neighboring water molecules.
How does water contribute to the oxygen in the air?
Water is the source of oxygen in the air through photosynthesis. Plants use water to produce oxygen as a byproduct, releasing it into the atmosphere.
How are hydrogen atoms from water used in biological processes?
The hydrogen atoms from water are used in many organic compounds, and form complex molecules necessary for life.
Why is water considered a universal solvent in biological reactions?
Water can dissolve a wide variety of substances, which facilitates chemical processes within organisms.
What roles does water play in chemical reactions?
Water acts as a reactant and a product in many chemical reactions, such as hydrolysis (where water is used to break down molecules) and condensation (where water is produced).
What is essential for life?
Water
What is cohesion?
The tendency of water molecules to stick to one another due to hydrogen bonds among molecules
What is adhesion?
The ability of water to stick to other substances, particularly those with charges on their surfaces (polar surfaces). Rainwater sticks and absorbs with cotton but runs off of rain jackets, usually consisting of rubberized fabrics.
What is capillary action?
The tendency of water to move in narrow tubes, even against the force of gravity. The water sticks to the glass and rises due to a combination of adhesive and cohesive forces.
Adhesion causes the water molecules to stick to the glass surface, while cohesion causes water molecules to stick together.
Why doesn’t capillary action work in wider tubes?
Because the adhesion is not strong enough to overcome the cohesion below.
What causes surface tension in water?
Cohesion between the water molecules at the surface of water
What does hydrophilic mean?
“Water-loving” substances interact easily with water. (polar and ionic compounds)
What does hydrophobic mean?
“Water-fearing” substances are not soluble in water (nonpolar molecules like oils, fats, greases, alkanes)
What are the three forms of water
Gas: steam becoming water vapor
Liquid: Around 50 degrees Celsius, water is made
Solid: Around 0 degrees Celsius, ice can be made, and it is less dense than water
What makes gas become a liquid?
Removing heat and thermal energy
Why does ice float
Because it is less dense than water, which allows life to continue beneath the ice.
What is specific heat capacity, and why does water have a high specific heat capacity?
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance by 1°C.
Water has a high specific heat capacity becase it needs to absorb much energy before its temperature changes. This property explains why boiling water takes a while.
Why is water’s high specific heat capacity important for life?
Water’s high specific heat capacity helps regulate temperature in living organisms and environments.
Because water requires a lot of energy to change temperature, it prevents rapid temperature changes that could lead to organisms evaporating.
What happens in pure water?
A small number of water molecules dissociate into hydrogen ions (H+) and hydroxide ions (OH-)
HOH<–> H+ + OH-
Why is pure water considered neutral?
The concentrations of hydrogen ions (H⁺) and hydroxide ions (OH⁻) are exactly equal in pure water.
Because these concentrations are equal, pure water is considered neutral, meaning it is neither acidic nor basic.
What is an acid
A substance that dissociates in solution to yield hydrogen ions (H+) and an anion, a proton donor.
HCL–> H+ + Cl- (anion)
What is a base?
A substance that dissociates in a solution yields a hydroxide ion (OH-) and a cation, a proton acceptor.
NaOH–> Na+ (cation) + OH-
What does the pH scale measure
The hydrogen ion
What makes a solution neutral?
Having a pH of 7 with equal concentrations of hydrogen ions and hydroxide ions
What makes a solution acidic
When the hydrogen ion concentration is higher than the hydroxide ion concentration, and the pH is less than 7.
What makes a solution basic
When the hydrogen ion concentration is lower than the hydroxide ion concentration and the pH is greater than 7.
What is the pH of more plant and animal cells (and their environment)
7.2-7.4