Chapter 2 Flashcards

A set of vocabulary flashcards defining fundamental chemical concepts, atomic components, subatomic particles, energy levels, and chemical bonds covered in Chapter 2.

Matter

Anything that takes up space and has mass.

Element

A substance that cannot be broken down to other substances by chemical reactions.

Compound

A substance consisting of two or more elements in a fixed ratio, possessing characteristics different from those of its elements.

Essential Elements

Elements required by an organism for life, with carbon, hydrogen, oxygen, and nitrogen making up $96\%$ of living matter.

Trace Elements

Elements required by an organism in minute quantities, accounting for less than $0.01\%$ of human body weight.

Atom

The smallest unit of matter that still retains the properties of an element.

Neutron

A subatomic particle with no electrical charge found in the atomic nucleus, possessing a mass close to $1\text{ Dalton}$.

Proton

A positively charged subatomic particle found in the atomic nucleus, possessing a mass close to $1\text{ Dalton}$.

Electron

A negatively charged subatomic particle that forms a cloud around the atomic nucleus.

Atomic Number

The number of protons in the nucleus of an atom, which equals the number of electrons in an electrically neutral atom.

Mass Number

The sum of protons plus neutrons in the nucleus of an atom.

Atomic Mass

The total mass of an atom, which is approximated by its mass number.

Isotopes

Two atoms of an element that differ in the number of neutrons in the nucleus and therefore have different mass numbers.

Radioactive Isotope

An isotope in which the nucleus spontaneously decays, giving off particles and energy.

Potential Energy

The energy that matter possesses because of its location or structure.

Electron Shells

Characteristic energy levels at average distances from the atomic nucleus where electrons are found.

Valence Electrons

Electrons located in the outermost shell of an atom that determine its chemical behavior.

Valence Shell

The outermost electron shell of an atom.

Orbital

The three-dimensional space where an electron is found $90\%$ of the time.

Chemical Bonds

Attractions that hold atoms close together through the sharing or transferring of valence electrons.

Covalent Bond

A chemical bond formed by the sharing of a pair of valence electrons by two atoms.

Molecule

Two or more atoms held together by covalent bonds.

Single Bond

A covalent bond representing the sharing of one pair of valence electrons.

Double Bond

A covalent bond representing the sharing of two pairs of valence electrons.

Valence

An atom's bonding capacity, which usually equals the number of unpaired electrons in its valence shell.

Electronegativity

An atom's attraction for the electrons in a covalent bond.

Nonpolar Covalent Bond

A covalent bond in which two atoms share electrons equally.

Polar Covalent Bond

A covalent bond between atoms where one atom is more electronegative, causing shared electrons to be pulled closer to it.

Ion

A charged atom or molecule.

Anion

A negatively charged ion.

Cation

A positively charged ion.

Ionic Bond

A chemical bond resulting from the attraction between oppositely charged anions and cations.

Ionic Compounds

Compounds formed by ionic bonds, also known as salts.

Hydrogen Bond

A weak chemical bond formed when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.

Van der Waals Interactions

Weak attractions between molecules or atoms that are very close together, caused by fleeting local charge differences.