CHEMICAL BONDING

• Nonmetals receive electrons and form negatively charged anions
• Metals give electrons and form positively charged cations
• The nature of atoms determines the type of chemical bond that can exist between them
• In ionic compounds, metals lose their outermost electron(s) to become positively charged ions (cations), whereas nonmetals gain these electrons to become negatively charged ions (anions).
• Covalent bonds are formed when two nonmetal atoms share pairs of electrons.
• Atoms combine to assume the stable configuration of a noble gas following the duet or octet rule
• Polar covalent bonds occur when there is unequal sharing of electrons due to differences in electronegativity
• Molecules may be composed of identical atoms (homonuclear) or different types of atoms (heteronuclear)
• Lewis structures show how valence electrons are arranged within a molecule
• Molecular geometry refers to the arrangement of atoms around a central atom in a molecule
• A molecule is a group of two or more atoms held together by one or more chemical bonds
• An ionic compound consists of a positive ion and a negative ion
• Nonmetals have high melting points, low boiling points, and poor conductors of heat and electricity.
• Metals have low melting points, high boiling points, and good conductors of heat and electricity.
• Ionic chemical bond contains positive ions immersed in a sea of mobile electrons
• The electrons in a bond between two iodine atoms are shared equally, and the resulting bond is nonpolar
• Polarity refers to the uneven distribution of charge within a molecule due to differences in electronegativity.
• Polyatomic ions are ions which consist of more than one atom
• In a polar covalent bond, the electron pair spends most of its time nearer to the more electronegative atom.
• Hydrogen, Beryllium, and Boron are exceptions to the octet rule
• Ionic bond is electrostatic in nature
• Ionic compounds are arranged in a crystal lattice
• Ionic compounds have high melting and boiling points. A high amount of energy is required to break the strong ionic bond that holds the ions in the lattice
• Ionic compounds are solids and nonconductors of electricity because ions are tightly packed in the crystal lattice
• When molten or dissolved in water, ionic compounds conduct electricity because ions dissociate in water and are free to move around. Such is the case for sodium chloride ($NaCl$)
• A covalent bond exists between two nonmetal atoms that share electrons to assume a stable configuration of noble gases such as helium (2 electrons) and neon (8 electrons)
• Lone pairs do not participate in chemical bonding