Chapter 2 - Chemical Principles

Chemistry

The study of interactions between atoms and molecules

Atom

smallest unit of matter

Molecules

Groups of two or more atoms held together by chemical bonds

Biosphere

Consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere.

Atoms are composed of

protons, neutrons, electrons

Protons

Positively charged particles

Electrons

Negatively charged particles

Neutrons

Uncharged particles

Nucleus

Made up of protons and neutrons

Electron shells

An energy level representing the distance of an electron from the nucleus of an atom.

Atomic number

the number of protons in the nucleus of an atom

Atomic mass

total number of protons and neutrons in an atom

Isotopes

Atoms of the same element that have different numbers of neutrons

Compound

Contains two or more kinds of atoms

Types of chemical bonds

ionic, covalent, hydrogen

Ionic bonds

Attractions between ions of the opposite charge

Ions

positively and negatively charged atoms

Cations

Lose electrons and have a positive charge

Anions

Gain electrons and have a negative charge

Covalent bonds

sharing of electrons; stronger and more common in organisms than ionic bonds

hydrogen bonds

Form when a hydrogen atom that is covalently bonded to an O or N (electronegative) atom is attracted to another N or O atom in another molecule

Chemical reactions

involve the making or breaking of bonds between atoms

endergonic reaction

absorbs energy

Exergonic reactions

Release energy

Types of chemical reactions

synthesis, decomposition, single replacement, double replacement, combustion

synthesis reaction

Occur when atoms, ions, or molecules combine to form new and larger molecules

decomposition reaction

A molecule is split into smaller molecules, ions, or atoms

Catabolism

Decomposition reaction in a cell

exchange reaction

Parts of the reacting molecules are shuffled around to produce new products