Biology 111 - Chapter 2 - FTCC

Matter refers to anything that has mass and occupies space.

What is matter?

Solid, liquid, gas, and plasma.

What are the four states of matter?

An element is a substance that cannot be broken down into different substances and is composed of one type of atom.

What is an element?

There are ninety-two naturally occurring elements.

How many naturally occurring elements are there?

CHNOPS, which stands for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

What acronym represents the six elements that make up 95% of the body weight of organisms?

An atom is the smallest part of an element that displays the properties of that element.

What is an atom?

Protons, neutrons, and electrons.

What are the three subatomic particles?

Protons have a positive charge and are located in the nucleus.

What is the charge and location of protons?

Neutrons have no charge and are located in the nucleus.

What is the charge and location of neutrons?

Electrons have a negative charge and negligible mass, located in electron shells.

What is the charge and mass of electrons?

The atomic number is equal to the number of protons in each atom of an element.

What does the atomic number represent?

The mass number is the sum of the number of protons and neutrons in the nucleus.

What is the mass number of an atom?

Isotopes are atoms of the same element that differ in the number of neutrons.

What is an isotope?

Radioactive isotopes are isotopes that spontaneously decay, giving off energy in the form of rays and subatomic particles.

What is a radioactive isotope?

Carbon-14 is an example of a radioactive isotope.

Give an example of a radioactive isotope.

Electrons determine the chemical behavior of atoms.

What determines the chemical behavior of atoms?

The Bohr model is a way to visualize electron location, showing electrons revolving around the nucleus in energy shells.

What is the Bohr model?

The first energy shell can hold up to 2 electrons.

How many electrons can the first energy shell hold?

Electrons are attracted to the positively charged nucleus, requiring energy to hold them in place and to push them away.

What is the relationship between electrons and energy?

Electrons have potential energy due to their relative position in the atom.

What is potential energy in the context of electrons?

The atomic mass is approximately equal to the mass number.

What is the atomic mass approximately equal to?

2 electrons.

What is the maximum number of electrons that the first energy shell can hold?

Up to 8 electrons.

How many electrons can each additional energy shell hold after the first?

The outermost energy shell of any atom.

What is the valence shell of an atom?

It determines many of an atom's chemical properties.

Why is the valence shell important?

The outermost shell is most stable when it has eight electrons.

What does the octet rule state?

If an atom has only one shell, the outermost valence shell is complete with two electrons.

What is the exception to the octet rule?

The number of electrons in the atom's valence shell.

What determines whether an atom gives up, accepts, or shares electrons?

Two or more of the same type of atoms bonded together.

What is a molecule?

A molecule containing at least two different elements bonded together.

What is a compound?

One molecule of glucose containing 6 carbon (C), 12 hydrogen (H), and 6 oxygen (O) atoms.

What does the formula C6H12O6 represent?

An atom that has lost or gained an electron.

What is an ion?

When electrons are transferred from one atom to another, creating oppositely charged ions that attract each other.

What forms an ionic bond?

The formation of sodium chloride (NaCl).

What is an example of an ionic bond?

A bond that results when two atoms share electrons to achieve an octet in their outer shell.

What is a covalent bond?

When electrons are shared equally between atoms.

When is a covalent bond considered nonpolar?

Hydrogen gas (H2), oxygen gas (O2), or methane (CH4).

What is an example of a nonpolar covalent bond?

Electrons are shared unequally between atoms.

What characterizes a polar covalent bond?

Water (H2O).

What is an example of a polar covalent bond?

The ability of an atom to attract electrons towards itself in a chemical bond.

What is electronegativity?

A weak attraction between a slightly positive hydrogen atom and a slightly negative atom.

What is a hydrogen bond?

The shape of a water molecule and its polarity allow for hydrogen bonding between molecules.

How does the polarity of water contribute to hydrogen bonding?

A single hydrogen bond is easily broken, while multiple hydrogen bonds are collectively quite strong.

How strong are multiple hydrogen bonds compared to a single hydrogen bond?

Hydrogen bonding allows water molecules to cling together, giving water many unique chemical properties.

What is the significance of hydrogen bonding in water molecules?

Water has a high heat capacity due to the many hydrogen bonds.

What property of water allows it to absorb large amounts of thermal energy without significant temperature change?

It helps organisms maintain their normal internal temperatures and protects them from rapid temperature changes.

How does water's high heat capacity benefit organisms?

Hydrogen bonds must be broken for water to evaporate, which cools bodies of organisms as their heat is used in the process.

What is the effect of hydrogen bonds on the evaporation of water?

Water is a good solvent because of its polarity, allowing polar substances to dissolve readily.

Why is water considered a good solvent?

Cohesion is the ability of water molecules to cling to each other, while adhesion is the ability of water molecules to cling to other polar surfaces.

What is the difference between cohesion and adhesion in water molecules?

Cohesion and adhesion account for water transport in plants and blood vessels.

How do cohesion and adhesion contribute to water transport in plants?

Hydrogen bonds become more rigid but also more open, causing water to expand as it freezes.

What happens to water at temperatures below 4°C?

Ice is less dense than liquid water, allowing it to float.

Why does ice float on liquid water?

pH measures the hydrogen ion concentration in a solution.

What is pH a measure of?

Water releases an equal number of hydrogen ions (H+) and hydroxide ions (OH-).

What occurs when water ionizes?

Acids dissociate in water, releasing hydrogen ions.

What defines acids in terms of their behavior in water?

Bases either take up hydrogen ions or release hydroxide ions.

What defines bases in terms of their behavior in water?

The pH scale ranges from 0 to 14, indicating acidity (0 to < 7), neutrality (7), and basicity (> 7 to 14).

What is the pH scale range and what do the values indicate?

Each unit change in pH represents a 10-fold change in H+ concentration.

How does a change in pH relate to hydrogen ion concentration?

The normal pH of human blood is 7.4, which is slightly basic.

What is the normal pH of human blood?

It results in acidosis, a life-threatening condition.

What are the consequences of blood pH dropping below 7.0?

It results in alkalosis, a life-threatening condition.

What are the consequences of blood pH rising above 7.8?

A buffer is a chemical or combination of chemicals that keeps pH within normal limits.

What is a buffer?

It dissociates and re-forms to reduce changes in pH, helping maintain stable blood pH.

How does the carbonic acid buffer work in the body?