Honors Biology - Unit 1

Acid

A substance that donates hydrogen atoms to solutions

Adhesion

The tendency of dissimilar materials to stick to each other due to attractive forces

Aqueous solution

A mixture where water acts as the solvent, dissolving another substance (the solute)

Atom

The basic unit of a chemical element

Atomic mass

the average mass of an element’s atoms, considering naturally occurring isotopes and their abundances

Atomic number

The total count of protons found in the nucleus of an atom, which uniquely identifies an element

Base

A substance that reduces the hydrogen ion concentration of a solution

Biology

The scientific study of life, encompassing living organisms and their fundamental processes, such as structure, function, growth, origin, and evolution.

Buffer

A substance that resists changes in pH, or the acidity/alkalinity of a solution, by absorbing or releasing hydrogen ions.

Chemical compound

A pure chemical substance formed when atoms of two or more different elements are chemically bonded together in a fixed ratio

Chemical reaction

A process where starting substances, called reactants, are changed into new and different substances, called products, by rearranging their atoms.

Cohesion

The act or state of sticking together

Covalent bond

A chemical link between two atoms where they share electron pairs to achieve a stable outer electron shell, holding them together in a molecule or compound.

Electron

a tiny, fundamental particle found in all atoms that carries a negative electric charge.

Electron shell

A distinct energy level or region around an atom’s nucleus where electrons are likely to be found, acting like an imaginary path or cloud.

Element

A pure substance made of only one type of atom, and it cannot be broken down into simpler substances by chemical means.

Heat

when thermal energy transfers from a warmer to a cooler body of matter

Homeostasis

The ability of a living organism to maintain a stable internal environment, such as temperature or blood sugar, even when the external environment changes

Hydrogen bond

A weak attraction that forms when a slightly positive hydrogen atom in one molecule is attracted to a slightly negative, highly electronegative atom in another molecule or part of the same molecule

Hydration shell

A layer of water molecules that surrounds a solute, like an ion or a polar molecule, when it dissolves in water

Ion

An atom or a group of atoms that has gained or lost electrons, giving it an overall positive or negative electric charge

Ionic bond

A strong chemical attraction between oppositely charged atoms, called ions, which forms when one atom transfers electrons to another, creating a stable and electrically neutral compound

Isotope

A version of a chemical element that has the same number of protons but a different number of neutrons compared to other versions of the same element

Mass number

The total number of protons and neutrons in the nucleus of an atom, also known as its nucleons

Matter

Anything that takes up space (has volume) and has mass

Molecule

The smallest part of a substance that can exist on its own, consisting of two or more atoms held together by chemical forces

Neutron

A subatomic particle found in the nucleus of an atom, alongside protons

Nonpolar covalent bond

A chemical bond where two atoms share electrons equally because they have the same or very similar electronegativity

Nucleus (of atom)

the tiny, dense, positivity lay charged center of an atom, containing protons and neutrons

pH scale

A measure of how acidic or basic a substance is, specifically focusing on the concentration of hydrogen ions in an aqueous solution

Polar molecule

A molecule with an unequal distribution of electron density, giving it a slightly positive end and a slightly negative end

Product

A new substance that is formed as a result of a chemical reaction

Proton

A tiny particle with a positive electrical charge, found in the center (nucleus) of every atom

Radioactive isotope

a form of an element with an unstable nucleus that emits radiation as it spontaneously changes into a more stable form

Reactant

A substance that starts a chemical reaction and changes into a different substance called a product

Trace element

Minerals present in living tissues in small amounts

Valence electron

An electron located in the outermost energy shell of an atom, which is involved in chemical bonding and chemical reactions

Solute

The substance that gets dissolved by another substance called the solvent, to form a homogeneous mixture called a solution

Solution

A type of mixture where one substance (the solute) is evenly dissolved into another substance (the solvent), forming a single, uniform substance that is homogeneous

Solvent

A substance that dissolves other substances, known as solutes, to form a solution

Surface tension

The elastic force on the surface of a liquid that causes it to shrink to the smallest possible area, like a stretched, tight film

Temperature

measures the intensity of heat (average speed of molecules in a body of matter).

Thermal energy

the energy associated with the random movements of atoms and molecules.

Biology

_______ is the study of life

A cell

What is the smallest unit of life that can exist on its own?

Homeostasis

Sweating pertains to which characteristic of life?

B. Exhibits movement

Which of the following is NOT an example of a characteristic a living organism must have?

A. Grows and develops

B. Exhibits movement

C. Evolves over time

D. Maintain homeostasis

D. Sodium

Which of the following is NOT one of the four most common elements in the human body?

A. Oxygen

B. Hydrogen

C. Nitrogen

D. Sodium

Protons and neutrons

Which particles are found in the NUCLEUS of an atom?

C. Electrons are found in the innermost shell

Which of the following statements about valence electrons is FALSE?

A. Electrons are found in the outermost shell

B. The more there are the more stable the atom is

C. Electrons are found in the innermost shell

D. Electrons are involved in bonding

Covalent bond

The type of bond where electrons are shared = ?

Ionic bond

The type of bond where electrons are lost or gained = ?

Nonpolar covalent bond

A ________ bond occurs when electrons are shared EQUALLY and the molecules have a linear shape

Polar covalent bond

A _____ bond occurs when electrons are NOT shared equally and the molecules typically have a bent shape

Negative

The oxygen in a molecule of water has what type of partial charge?

Positive

The hydrogen in a molecule of water has what type of partial charge?

Polar covalent bond

The type of bond that forms between the oxygen and hydrogen within a water molecule

Hydrogen bonds

Weak bonds that form between a hydrogen atom and a negatively charged atom of a nearby molecule = ?

Cohesion

? = when water molecules stick together

Adhesion

? = when water molecules stick to other things

Hydrogen bonds

Water’s surface tension is caused by ________

Capillary action

What property of water enabled these flowers to change color?

Molecules become closer together

As ice melts do molecules become closer together or farther apart?

D. Its molecules create stable hydrogen bonds

Why does ice float?

A. Hydrogen bonds constantly break/reform since they’re weak

B. Its molecules move farther apart

C. Nothing changes with the water molecules

D. Its molecules create stable hydrogen bonds

Substance being dissolved

Is the solute the substance doing the dissolving or being dissolved?

substance doing the dissolving

Is the solvent the substance doing the dissolving or the substance being dissolved?

True

A buffer helps prevent sharp, sudden changes in pH. True or false?

pH scale

? = describes how acidic or basic a solution is