ch 11: chemical bonds

metal properties

usually lustrous, malleable, and good heat/electrical conductors

metal properties

tend to lose electrons to form cations

nonmetal properties

usually not lustrous, brittle, poor heat conductors

nonmetal properties

tend to gain electrons to form anions

metalloid properties

can have some properties of either metals or nonmetals

atomic radius

increases down a group and decreases left to right across a period

down a group

additional n quantum levels are added; electrons are farther from the nucleus, so size increases

across a period

left to right, n remains constant but atomic number increases

across a period

increased nuclear charge creates greater interaction with electrons, resulting in a decrease in radii

ionization energy

energy required to remove an electron from an atom

1st ionization energy

energy needed to remove the first electron

2nd ionization energy

energy needed to remove the second electron

succesive ionizations

always increase in energy as the remaining electrons feel stronger attraction to resulting cation produced

ionization energy

generally decreases down a group and increases left to right across a period

down a group

electron removed is from a higher n level; farther from the nucleus, it feels less interaction, making it easier to remove

across a period

left to right, n remains constant but atomic number increases

across a period

increase in + nuclear charge creates a greater interaction with electrons, making it more difficult to remove outer electrons

noble gas

extreme amounts of energy needed to remove electrons from these configurations

lewis structures of atoms

valence electroms in an atom are responsible for the formation of chemical bonds between atoms

lewis structures

simple way of representing atoms and their valence electrons

lewis structures

use dots to represent valence electrons of an atom

main group elements

group number gives number of valence electrons

main group elements

tend to attain an outer electron configuration that resembles stable noble gases

second period and below

most stable configuration consists of eight electrons in valence energy level

ionic bond

attraction between oppositely charged ions

ionic bond

more than one electron can be transferred between a metal and nonmetal

ionic compounds

charge neutral

noble gas

in almost all stable compounds of main group elements, all atoms attempt to attain this configuration

electronegativity

a measure of the ability of an atom to attract electrons in a covalent bond

electronegativity

increases left to right across periodic table

electronegativity

decreases down a main group

bond polarity

determined by difference in electronegativity of two atoms sharing electrons

nonpolar

if atoms in covalent bond are the same, bond is this, and electrons are shared equally

ionic

if difference in electronegativities is >2, bonding is considered…

polar covalent

if difference in electronegativities is <2, bonding is considered…

symmetric arrangements

of polar bonds result in nonpolar molecules

asymmetric arrangements

of polar bonds result in polar molecules

dipole

may be written as a vector arrow w/ arrow pointing toward negatively charged end of the molecule

dipole

molecule is polarized with negatively and positively charged regions

dipole

molecules which are electronically asymmetric have a permanent…

valence electrons

equal to group number for main group elements

resonance structures

multiple lewis structures which can represent the same molecule

polyatomic ion

stable group of atoms that form an ion and behave as a single unit

valence shell electron pair repulsion theory

VSEPR theory

valence shell electron pair repulsion theory

theory developed to help predict the geometry of molecules based on bonding and nonbonding electrons around a central atom

electrostatic repulsion

molecules adopt geometries to minimize this between electron pairs

linear geometry

results when two electron pairs surround central atom

linear geometry

maximizes distance of bonding pairs

trigonal planar geometry

results when three electron pairs surround a central atom

tetrahedral geometry

results when four electron pairs surround a central atom