Basic Chemistry Concepts
Atoms and Subatomic Particles
Atom: The smallest unit of an element that retains the element’s properties. Nucleus: The dense core of an atom, containing protons and neutrons, and holding most of the atom’s mass. Proton: A positively charged subatomic particle found in the nucleus with a mass of 1 atomic mass unit (amu). Neutron: A neutral subatomic particle found in the nucleus with a mass of 1 amu. Electron: A negatively charged subatomic particle found outside the nucleus with negligible mass. Atoms can gain, lose, or share electrons in chemical reactions.
Charge: The electrical property of an atom determined by the difference between the number of protons and electrons. A neutral atom has equal numbers of protons and electrons. Ion: An atom or molecule with a net charge due to the gain or loss of electrons. Atomic Number (Z): The number of protons in an atom’s nucleus, unique to each element. Mass Number (A): The total number of protons and neutrons in an atom’s nucleus. Atomic Mass: The actual mass of an atom, close to the mass number. Isotopes: Atoms of the same element with different numbers of neutrons and, therefore, different mass numbers.
Elements and Symbols
Element Symbol: A one- or two-letter abbreviation for an element, with the first letter capitalized and subsequent letters lowercase. Chemical Symbol: A notation showing an element’s symbol, atomic number, mass number, and charge.
Waves
Wavelength (λ): The distance between corresponding points on adjacent waves. Frequency (f or ν): The number of waves passing a point per unit time. Electromagnetic waves, like light, travel at the speed of light (c = 3.00 × 108 m/s).
Chemical Bonds
Ionic Bond: A bond formed by the electrostatic attraction between oppositely charged ions, typically between a metal and a nonmetal. Covalent Bond: A bond formed by the sharing of electrons between atoms, typically between nonmetals. Metallic Bond: A bond formed by a “sea of electrons” shared among metal atoms. Chemical Bond or Intramolecular Bond: A strong bond between atoms or ions within a molecule. Intermolecular Bond: A weaker bond between molecules.
Acids
Acid: A compound that releases hydrogen ions (H+) in water. The naming of acids is based on the anion present.
