Chapter 2: Basic Chemistry

Matter

Anything that takes up space and has mass

Element

A substance that cannot be broken down into simpler substances with different properties

Property

Physical of chemical characteristic of a substance

Atom

The smallest particle of an element (element and its atoms have the same name)

Atomic symbol

One or two letters that represent the name of an element

3 Main Subatomic Particles

Protons, neutrons, electrons

Protons

Positively charged subatomic particles

Neutrons

Neutrally charged subatomic particles

Electrons

Negatively charged subatomic particles

Electron Shell

The circle that represents the average location of electrons

Atomic Number

Number of protons in the nucleus

Mass number

The total number of protons and neutrons in the nucleus

Atomic mass

Average mass number for all isotopes of an element

Atom on a periodic table

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Isotopes

Atoms of the same element that have different numbers of neutrons

Tracer

A substance added to a biological system to track its behavior, distribution, and processes at the molecular, cellular, or systemic level

Neutral atom

Positive charges are balanced by equal amount of negative charges

Bohr model

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Octet rule

If an atom has more than one shell: the outermost shell is most stable when it has 8 electrons

Which element does not follow the octet rule?

Hydrogen and Helium

How many electrons do hydrogen and helium need to be most stable?

Two electrons (duet rule)

Valence shell

Atoms outermost shell, determines whether atom gives up or accepts electrons

Molecule

Two or more elements bonded together, smallest part of a compound that retains its chemical properties

Compound

A molecule containing at least 2 different elements

Formula

Tells you the number of each kind of atom in a molecule (ex. C6H12O6)

Ions

Charged particles

Ionic Bond

Ionic compounds held together by a strong attraction between negatively and positively charged ions

Salts

Solid substances that usually separate and exist as individuals (ex. sea salt breaks apart as is it put in water)

Ionic bond vs ionic compound

Ionic bond is the process of electrons being transferred between two atoms, while ionic compound is the connection between those atoms as a result

Covalent bond

Two atoms share electrons in such a way that each atom has an octet of electrons in the outer shell

Nonpolar covalent bond

The sharing of electrons between two electrons is equal

Electronegativity

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

Polar covalent bond

Electrons are not shared equally among atoms due to different electronegativities

Hydrogen bond

The attraction of a slightly positive hydrogen to a slightly negative atom near it (like oxygen, nitrogen, or fluorine)

Calorie

The amount of heat energy need to raise the temperature of 1g of water to 1 degree C

Solution

Combination of solutes

Solute

Dissolved substances

Hydrophilic

Molecules that can attract water

Hydrophobic

Nonionized and nonpolar molecules that cannot attract water

Surface tension

Force that holds moist membranes together due to the attraction of water molecules through hydrogen bonds

Hydrogen ions (H+)

One of two ions that results when a water molecule separates, hydrogen ion that has lost is electron, causing it to have a positive charge

Acids

Substances that separate in water, releasing hydrogen ions (H+)

Hydroxide ions (OH-)

One of two ions that results when a water molecule separates, it has gained an electron, has a negative charge

Bases

Substances that either take up hydrogen ions or release hydroxide ions

pH scale

Scale used to measure the acidity or basicity/alkaninity of a solution

Buffer

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

Cohesion

Molecules are attracted to each other