Transcript PPT
Essential Principles of Chemistry Lecture 3 Generalized Atomic Structure Nucleus houses the massive particles (protons and neutrons) # Protons = Atomic Number # Protons + Neutrons = Atomic Mass Responsible for mass and density Electrons lie in orbitals that surround the nucleus # Electrons = # Protons If not, then it is an ION Responsible for bonding Ions Ions are electrically charged particles formed by the gain or loss of electrons Cations are positively charged Anions are negatively charged Metals are elements that readily form cations Non-Metals are elements that readily form anions Electron Orbitals Alkali Metals Alkali Earth Metals Transition Metals Metaloids Other Metals Non-Metals Halogens Noble Gases Decreasing Atomic Radius Decreasing Atomic Radius Electronegativity: measure of an atom’s ability to attract electrons in a chemical bond Ionic Bonds An atom with lower electro negativity transfers one or more electrons to an atom with higher electronegativity Metal with non-metal Results in charged ions Oppositely charged ions are attracted and thereby form a weak bond Ionic Bonds Ions are not actually “attached” and so bonds are relatively weak Soft minerals Ions can be attracted by other charged ions or molecules Soluble in water Covalent Bonds Two atoms with approximately equal electronegativity share one or more electrons Results in a merging of the electron clouds, and thereby forms a strong bond Hard minerals Metallic Bonds Delocalized sharing of free electrons among a lattice of metal atoms with little or no difference in electronegativity Results in one continuous electron cloud Soft, malleable minerals that conduct both heat and electricity Natural Bonds Usually Share Characteristics Van der Waal’s “Bonds” Attraction between atoms, ions or molecules that have an imbalance in the distribution of electrons (dipole) Fleeting and fluctuating weak attractions Soft minerals with a low melting point Allows for the basal cleavage in micas