lewis structures

expanded octet

where a central atom in a molecule holds more than eight valence electrons, violating the standard octet rule

when dose the expanded octet rule occur

it occurs with elements in period 3 and below

why can elements after period 3 use the expended octet rule

By utilizing their d orbital

resonances

are different ways to represent the same molecule by redistributing electrons among bonds

formal charge

calculated charge assigned to an individual atom within a molecule or ion to determine the most plausible Lewis structure

how is formal charge used to predict when a centrel atom will have an incomplete or expanded octet

helps identify the most stable Lewis structure by minimizing charge separation ( is ideal). If using the octet rule results in large formal charges (e.g., or ) on a central atom, it suggests an expanded octet (more bonds) is necessary to bring the charge closer to , or an incomplete octet (fewer bonds) is acceptable

how is formal charge used to predict the correct structure from several Lewis dot structers that the octet rule deems valid

by calculating the hypothetical charge distribution among atoms, allowing chemists to select the most stable and realistic structure.

when dose a covalent compound have a resonances structure?

more than one valid picture (Lewis structure) for the same molecule

non meticallic and metalloids are

covelent bonds

Ionic compounds (metal + nonmetal) don't use prefixes because

their ratios are fixed by charge balancing,

Covalent compounds (nonmetal + nonmetal) use prefixes (di-, tri-, tetra-) because

, e.g., . Covalent compounds (nonmetal + nonmetal) use prefixes (di-, tri-, tetra-) because they can combine in multiple ratios, e.g., vs. . Ionic uses roman numerals to specify metal charge.

transisition metals are located from

groups 3 to 12 on the periodic table.

Roman numerals are used in naming ionic compounds containing

metals that can have multiple charges (usually transisition metals)

Without a numeral, "iron chloride" could mean two different substances

The numeral clarifies exactly which metal ion is present.

roman numerals represent the charge not the

amount of valence e-s

what is Electronegativity

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.

electronegativty increases from where to where in the periodic table

increases from bottom left to top right

other elements included as transition mentals when naming chemical formulas

lead, tin, iron (Fe), copper (Cu), zinc (Zn), titanium (Ti), nickel (Ni), cobalt (Co), tungsten (W), gold (Au), silver (Ag), platinum (Pt), and manganese (Mn

tetra

4

penta

5

hexa

6

hepta

7

octa

8

nona

9

deca

10

equation to figure out how many lone pairs there are

LP= Ve-8(n= number of atoms)/ 2

LP stands for

one pair of e-s