Complete each statement below by choosing a term from the following list. Terms may be used more than once. main-group elements halogens metals transition metals alkaline earth metals alkali metals hydrogen noble gases
The have a single electron in the highest occupied energy level.
The are in the s- and p-blocks of the periodic table.
All the have two valence electrons and get to a stable electron configuration by losing two electrons.
Unlike the main-group elements, each group of the does not have the identical outer electron configuration.
The , the most reactive group of non-metals, achieve stable electron configurations by gaining one electron.
The have a full set of electrons in their outermost energy level.
The are very stable and have low reactivity.
The are highly reactive and readily form salts with metals.
In general, the are metals that are less reactive than the alkali metals and the alkaline earth metals.
The are metals that lose one electron when they react with water to form alkaline solutions.
Most elements are .
With its one valence electron, reacts with many other elements.

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years

the dissolution of polymer can be thermodynamically described in 2 steps.

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l