Is light made up of atoms and elements? •explain the relationship between matter, atoms, and elements.. •distinguish between elements and compounds.. •describe molecules, and explain how they are formed.. •interpret and write some common chemical formulas.. •categorize materials as pure substances or mixtures..

Secondly, a mixture is a combination of two or more substances which are not united using a chemical procedure. The components that make up a mixture do not exist in fixed proportions, and most of the natural substances that you are familiar with, are mixtures. Examples of mixtures include water, alcohol, oil, and dye.

So what are the distinct differences between these two? With regards to a mixture, it can be physically separated into pure compounds or elements. This is something that is not possible with a pure substance, because it is already a type of matter which exists in its most basic, or purest form.

Another distinct characteristic of a pure substance is that, no matter how physically impossible it may be to isolate a pure substance, it can only be considered as pure if no impurities are detected. When it comes to their physical properties, such as their boiling or melting points, pure substances are non-changing, while mixtures are varying. For example, the boiling point of pure water is at 100 degrees Celsius, while the boiling point of alcohol mixed with water may be at a range of temperatures. To put it simply, pure substances are exactly what the name implies – pure, while mixtures are impure.

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