Chapter 2 - The Nature of Molecules and the Properties of Water

The polarity of water.

Any substance in the universe that has mass and occupies space.

Hydrogen bonds.

Protons, neutrons, and electrons.

Slightly positive charge.

In the nucleus.

Slightly negative charge.

Negatively charged.

The attraction of oppositely charged ions.

It usually has 1 proton and no neutrons.

Attractions between ions of opposite charge.

Letters starting with K, L, M, etc.

It loses an electron to become Na+.

It is critical to understanding the nature of biological molecules.

The type of interaction that can occur between atoms.

Any substance that dissociates in water to increase the [H+] and lower the pH.

An acid.

A tetrahedron, with δ- at the H and δ+ at the O.

Energy level K.

It gains an electron to become Cl−.

An enormous explosion that probably signaled the beginning of the universe.

A transfer of electrons, creating positive and negative ions that attract each other.

Atoms tend to establish completely full outer energy levels, typically one filled s orbital and three filled p orbitals.

The stronger an acid is, the more hydrogen ions it produces and the lower its pH.

A single s orbital called 1s.

It has a low pH.

Hydrogen bonds.

The attraction of opposite charges.

When atoms share 2 or more valence electrons.

Approximately 3.5 billion years ago.

The sharing of electrons between two atoms.

Helium, which has only one shell with 2 electrons.

A substance that combines with H+ dissolved in water, thus lowering the [H+].

Up to 8 electrons.

Four.

Cohesion, due to hydrogen bonding between water molecules.

They can disrupt the forces holding ions together.

No net charge, satisfies the octet rule, and no unpaired electrons.

94 naturally occurring elements.

A bond involving unequal sharing of electrons, resulting in regions of partial charge.

Buffers resist changes in pH by releasing hydrogen ions when a base is added and absorbing hydrogen ions when acid is added.

2s (2 electrons) and 2p (6 electrons in pairs).

Cohesion is the attraction between water molecules, while adhesion is the attraction between water molecules and other polar molecules.

It would be soluble in water.

The number of shared electrons.

Na is oxidized and Cl is reduced.

Carbon, hydrogen, oxygen, and nitrogen.

Reactants are the original molecules, and products are the molecules resulting from the reaction.

Buffers keep [H+] relatively constant and minimize changes in pH.

Capillary action, due to adhesion of water molecules to the sides of the tube.

Because its energy levels K and L are completely filled with electrons.

Atoms with very different electronegativity.

It fills the valence electron energy level, making bonded atoms more stable.

A lattice of Na+ and Cl−.

Molecules containing more than one type of element.

Temperature, concentration of reactants and products, and catalysts.

A pair of molecules, one an acid and one a base.

1 calorie/g/°C.

The electron moves to a higher energy level, farther from the nucleus.

An atom's affinity for electrons.

Sodium becomes a cation (Na+) and chlorine becomes an anion (Cl−).

They have all eight electrons in the valence shell.

Its ability to form hydrogen bonds.

A condition where human blood pH drops from the normal 7.4 to ~7.1, which can be fatal if not treated.

Loss of an electron.

Because of the many hydrogen bonds that need to be broken.

Equal sharing of electrons.

Because the bonds between oxygen and hydrogen are highly polar, with oxygen being more electronegative.

They have the same number of valence electrons.

A condition where blood pH rises up to 7.7, which is also serious.

Gain of an electron.

They are responsible for many of water's important physical properties.

Unequal sharing of electrons.

Some trace elements are very important for biological functions.

Oxygen becomes partially negative (δ–) and hydrogen becomes partially positive (δ+).

Chemical energy.

Oxygen has a greater affinity for electrons than hydrogen, leading to unequal sharing.

586 calories per gram.

It cools the surface from which it evaporates, such as in sweating.

Because hydrogen bonds in ice space the water molecules relatively far apart.

It allows ice to float, keeping the water beneath liquid and protecting aquatic life.

Polar molecules and ions, such as sugar and salt.

The process by which water organizes nonpolar molecules, causing them to aggregate.

It can be spontaneously broken, leading to ionization.

Neutral, with a [H+] of 10^-7.

The number of protons in an atom.

They have the same number of protons and electrons.

A substance that cannot be broken down into simpler substances by ordinary chemical means.

It is the sum of protons and neutrons in an atom.

Mass refers to the amount of substance, while weight refers to the force of gravity on that substance.

Negatively charged particles located in orbitals that occupy most of the volume of the atom.

Charged particles that are unbalanced in terms of protons and electrons.

A particle with more protons than electrons, resulting in a net positive charge.

A particle with fewer protons than electrons, resulting in a net negative charge.

Atoms of a single element that possess different numbers of neutrons.

An unstable isotope that emits radiation as its nucleus breaks up.

The time it takes for half of the atoms in a sample to decay.

The number and arrangement of electrons in their orbitals are key to an atom's chemical behavior.

Electrons in discrete orbits around the nucleus.

An area around a nucleus where an electron is most likely to be found.

No orbital can contain more than two electrons.