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Flashcards in Chapter 2 Deck (54):
1

Matter

Anything that occupies space and has mass.

2

Element

Is a substance that cannot be broken down to other substances by ordinary chemical means. (92 in nature)

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Compound

Is a substance consisting of two or more different elements combined in a fixed ratio.

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make up 96% of all living matter.

Oxygen, Carbon, Hydrogen, and Nitrogen

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Trace Elements

Are essential for humans, but only in minute quantities.

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Iodine deficiency

causes the thyroid gland to grow to abnormal size, a condition called goiter.

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commonly added minerals to food

Iron , Fluoride

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Atom

Is the smallest unit of matter that still retains the properties of an element

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Proton

Is a subatomic particle with a single positive electrical charge. (+)

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Electron

Is a subatomic particle with a single negative charge. (-)

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Neutron

Is electrically neutral. (no charge)

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Nucleus

atoms central core. (2 Protons, 2 Neutrons)

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Atomic Number

All the atoms of a particular element have the same unique number of protons.v

14

Mass Number

Is the sum of the number of protons and neutrons in its nucleus.

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Atomic Mass

is approximately to its mass number the sum of its protons and neutrons in daltons.

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Mass number vs atomic mass

All atoms of an element have the same atomic number, but some atoms of that element may differ in mass number. (This is because of Isotopes)

17

Isotopes

The different isotopes of an element have the same number of protons and behave identically in chemical reactions, but they have different numbers of neutrons.

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Radioactive Isotope

is one in which the nucleus decays spontaneously, giving off particles and energy

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use of isotopes

isotopes can be used to track certain body functions by finding where the isotopes are in the body.

20

Electron Shells

the location of electrons from the nucleus, each with a characteristic distance.

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first orbital and second orbital

The first orbital can hold 2, the second can hold 8 (4 pairs).

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Valence Shell

is the number of electrons present in the outermost shell

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Chemical Bonds

when two atoms with incomplete outer shells react, each atom will share, donate, or receive electrons so both have complete outer shells.

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Covalent Bond

two atoms, each with an unpaired electron in its outer shell, actually share a pair of electrons.

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Molecule

Are atoms held together by covalent bonds.

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Valence or bonding capacity

is the number of additional electrons needed to fill its valence shell.

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Electronegativity

an atom’s attraction for shared electrons.

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Non-polar covalent bonds

electrons that are shared equally between the atoms.

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Polar covalent bond

the pulling of shared negatively charged electrons closer to the more electronegative atom makes that atom partially negative and the other atom partially positive. (electron not shared equally)

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Ion

an atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons.

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Ionic bond

Two Ions with opposite charges attract each other.

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Ionic bonds form

when one atom transfers an electron to another.

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Salt

a synonym for an ionic compound (Sodium Chloride).

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The fullness of a valence shell

determines the pattern of covalent bonding or ionization.

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Most strong bonds

are covalent.

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Hydrogen bond

one of the most important types of weak bonds

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what are the charges in a hydrogen bond

Oxygen slightly negative, Hydrogen slightly positive.

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Polar molecule

it has an un-equal distribution of charges

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Chemical Reactions

breaking existing chemical bonds and forming new ones.

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Cohesion

Tendency of molecules of the same kind to stick together.

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Adhesion

the cling of one substance to another.

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Surface tension

a measure of how difficult it is to stretch or break the surface of a liquid.

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Thermal energy

is the energy associated with the random movement of atoms and molecules.

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Heat

thermal energy transferred from warm to cold.

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Temperature

measures the intensity of heat, that is the average speed of molecules in a body of matter.

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Evaporative cooling

when a substance evaporates the surface of the liquid that remains behind cools down.

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Solution

is a liquid consisting of a uniform mixture of two or more substances.

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Solvent

The dissolving agent

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Solute

a substance that is dissolved

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Aqueous solution

is one in which water is the solvent

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Why is water a universal solvent

Positive hydrogen ends of water molecules attract to negative ions.
Negative Oxygen ends of water molecules attracted to positive sodium ion.

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Acid

Donates hydrogen ions (H+)

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Base

is a substance that reduces the hydrogen ion concentration of a solution. (OH-)

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Buffer

A substance that accepts H+ when they are in excess and donates H+ when their concentration drops is called a buffer.