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

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

In the nucleus.

It usually has 1 proton and no neutrons.

Energy level K.

The attraction of opposite charges.

Slightly positive charge.

The attraction of oppositely charged ions.

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

Negatively charged.

The type of interaction that can occur between atoms.

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

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

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

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

An atom's affinity for electrons.

It loses an electron to become Na+.

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

The sharing of electrons between two atoms.

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

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

1 calorie/g/°C.

Hydrogen bonds.

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

A single s orbital called 1s.

Up to 8 electrons.

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

Equal sharing of electrons.

Slightly negative charge.

Attractions between ions of opposite charge.

It gains an electron to become Cl−.

When atoms share 2 or more valence electrons.

94 naturally occurring elements.

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

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

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

The polarity of water.

It is critical to understanding the nature of biological molecules.

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

Helium, which has only one shell with 2 electrons.

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

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

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

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

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

The number of protons in an atom.

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

No orbital can contain more than two electrons.

Letters starting with K, L, M, etc.

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

Approximately 3.5 billion years ago.

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

Carbon, hydrogen, oxygen, and nitrogen.

Temperature, concentration of reactants and products, and catalysts.

Loss of an electron.

Some trace elements are very important for biological functions.

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

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

Protons, neutrons, and electrons.

An acid.

It has a low pH.

Four.

It would be soluble in water.

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

They have all eight electrons in the valence shell.

Gain of an electron.

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

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

Electrons in discrete orbits around the nucleus.

Hydrogen bonds.

Cohesion, due to hydrogen bonding between water molecules.

The number of shared electrons.

A lattice of Na+ and Cl−.

Its ability to form hydrogen bonds.

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

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

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

They can disrupt the forces holding ions together.

Na is oxidized and Cl is reduced.

Molecules containing more than one type of element.

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

Unequal sharing of electrons.

Polar molecules and ions, such as sugar and salt.

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

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

Atoms with very different electronegativity.

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

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

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

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

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

They have the same number of valence electrons.

586 calories per gram.

They have the same number of protons and electrons.

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

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

It can be spontaneously broken, leading to ionization.

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

Chemical energy.

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

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

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