Essential Principles of Chemistry Lecture 3

Generalized Atomic Structure Nucleus houses the massive particles (protons and neutrons) 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 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 Ions are electrically charged particles formed by the gain or loss of electrons Cations are positively charged Cations are positively charged Anions are negatively charged Anions are negatively charged Metals are elements that readily form cations Metals are elements that readily form cations Non-Metals are elements that readily form anions 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

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 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 Results in charged ions Oppositely charged ions are attracted and thereby form a weak bond Oppositely charged ions are attracted and thereby form a weak bond

Ionic Bonds Ions are not actually “attached” and so bonds are relatively weak Ions are not actually “attached” and so bonds are relatively weak Soft minerals Ions can be attracted by other charged ions or molecules 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 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 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 Delocalized sharing of free electrons among a lattice of metal atoms with little or no difference in electronegativity Results in one continuous electron cloud 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) Attraction between atoms, ions or molecules that have an imbalance in the distribution of electrons (dipole) Fleeting and fluctuating weak attractions Fleeting and fluctuating weak attractions Soft minerals with a low melting point Allows for the basal cleavage in micas