Valence electrons are located in the outermost electron shell. Elements in same vertical column have same number of valence electrons. Group number determines valence electrons: 1-8 electrons. Helium has 2 electrons, group 18 has 8 (except He)
Electron configuration shows the arrangement of electrons in atomic orbitals. Electrons orbit around nucleus in different-shaped regions called shells. Each shell contains electrons with same energy level
Periodic table organizes elements by atomic structure and color-coding. Elements are arranged by atomic number in three main groups. Atomic number appears above element symbol in upper left corner
There are 118 elements on the periodic table. Elements are identified by their atomic number, which equals the number of protons. Elements are arranged in order of increasing atomic number
Atoms are the fundamental building blocks of matter and chemistry. Most of an atom is empty space, containing protons, neutrons, and electrons. Protons and neutrons form the positively charged nucleus. Electrons orbit the nucleus in shells, each holding specific numbers of electrons
IUPAC has officially identified and named 118 chemical elements. Elements are defined by specific number of protons in atomic nucleus. Periodic table visualizes all 118 elements by chemical properties. Elements can be organized by proton number or other properties. List format can be linear or arranged by chemical symbols