Covalent Bonding Covalent bonding occurs between two non-metals A covalent bond involves the electrostatic attraction between nuclei of two atoms and the bonding electrons of their outer she...
Physical Properties of Ionic Compounds Most ionic, metallic and covalent solids are crystalline lattices The ions, atoms or molecules are arranged in a regular and repeating arrangement Gian...
Ionic Radius Ionic radius The ionic radius of an element is a measure of the size of an ion Ionic radii show predictable patterns Ionic radii increase with increasing negative charge Ionic r...
Ionic Dot-and-Cross Diagrams Dot and cross diagrams are diagrams that show the arrangement of the outer-shell electrons in an ionic or covalent compound or element The electrons are shown as...
Ionic Bonds As a general rule, metals are on the left of the periodic table and nonmetals are on the right-hand side Ionic bonding involves the transfer of electrons from a metallic element to a no...
Melting & Boiling Point Trends Elements in the periodic table are arranged in order of increasing atomic number and placed in vertical columns (groups) and horizontal rows (periods) The ...
NEC全美经济学挑战（National economic challenge）由美国经济教育学会举办的经济学学术活动。它是美国最负盛名、最具影响力的中学生经济学学术活动。AP课程 VS NEC，2022新赛季报名中！ NEC的知识体系与多种主要...
Electronic Configurations of Atoms & Ions The principal quantum shells increase in energy with increasing principal quantum number E.g. n = 4 is higher in energy than n = 2 The su...
Orbital Shapes Orbitals Subshells contain one or more atomic orbitals Orbitals exist at specific energy levels and electrons can only be found at these specific levels, not in between them E...
