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in English·
1 Dec 2022

MODERN PERIODIC TABLE

The periodic table is a tabular arrangement of the chemical elements organized on the basis of their atomic numbers, electron configurations, and chemical properties.

Elements are presented in order of increasing atomic number (the number of protons in the nucleus). The standard form of the table consists of a grid of elements laid out in 18 columns and 7 rows, with a double row of elements below that. (Please see periodic table provided above.)

The horizontal rows of the table are called periods and the vertical columns are called groups. The periodic table incorporates recurring trends and can therefore be used to derive relationships between the properties of the elements and predict the properties of new, yet to be discovered or synthesized, elements. As a result, a periodic table provides a useful framework for analyzing chemical behavior.

 

Main group (or representative) elements include elements (except hydrogen) in groups 1 and 2 and groups 13 to 18. In older nomenclature, the main group elements are groups lA and lIA, and groups IIIB to O (CAS groups IIIA to VIIIA).

The elements in groups 3 to 12 are the transition elements, the focus of this exercise.

Transition elements are divided into two groups:

the transition metals

the inner transition metals

 

The two sets of inner transition metals are located along the bottom of the periodic table and are known as the lanthanide series and the actinide series. (See periodic table provided above.) The rest of the elements in groups 3 to 12 are transition metals.

Transactinide elements (also called transactinides, or super-heavy elements) are the elements with atomic numbers greater than those of the actinides. (The heaviest actinide is lawrencium (103).)

Transuranium (or transuranic) elements are those elements having an atomic number greater than that of uranium (92), an actinide. (Thus all transactinide elements are also transuranium elements.)

 

Transuranium elements are unstable and decay radioactively into other elements.

These elements were all first discovered in the laboratory, with neptunium, plutonium, americium, curium, berkelium, and californium later also discovered in nature.

Transuranium elements can be synthesized in the laboratory through the use of nuclear reactors or particle accelerators.

Please review the following questions:

1. Are all transactinide elements transuranium elements?

2. Are all tranuranium elements actinides?

 

3. List two unique properties of transuranium elements:

A.

B.

 

For the following symbols, provide the element name and indicate whether it is a representative element, a lanthanide, an actinide, or a transactinide element.

4. Cf

5. Pm

6. Ag

7. Ds

8. Tb

 

9. Rf

10. U

in English·
1 Dec 2022

Balancing chemicals equation

All the information I was given is in the picture please look at them thanks and make your work is not copied off of Google

Chemical equations use formulas to show the identities and relative amounts of substances in a reaction. We must balance chemical equations because of the law of conservation of mass.
 
Complete the following assignment either below or on your own paper, if necessary:
State the law of conservation of mass:
 
This means that if you have 7 g of reactants, the total mass of the products is 7 g.
If you react 2.00 g of hydrogen completely using 15.87 g of oxygen to produce water, how much water (in grams) will you have?
 
To balance a chemical equation, we use coefficients to indicate the amount of each substance that must be consumed or produced for the reaction to obey the law of conservation of mass. There must be the same number each atom on both sides of the equation. For example, the reaction is balanced - each side had 1 C atom and 2 O atoms. As long as the total number of each type of atom is the same on both sides of the equation, it is balanced.
 
Being able to balance equations is crucial in chemistry. Use the following phrases that are randomly arranged below to complete the flow chart on the next page to help you develop a systematic approach to balancing chemical equations.
Write skeletal equation
Reduce coefficients to lowest possible ratio Check to make sure equation is balanced
Count atoms
Reactants
Products
Add coefficients on each side of reaction. Adjust if necessary
Number of atoms for each reactant element
Number of atoms for each product element
 
in English·
1 Dec 2022

Half life

All the information I was given is in the picture please look at them thanks and make your work is not copied off of Google

The half-life $\left(\mathrm{t}_{1 / 2}\right)$ of a radioactive substance is the amount of time required for half of the unstable, radioactive atoms in a sample to undergo radioactive decay.
 
This relationship is modeled mathematically through exponential decay, relating the quantity of substance initially and finally present, the mean lifetime of the decaying quantity, the decay constant, and the half-life. You will have an opportunity to work with the actual equation in more advanced math and science courses.
 
In this lesson, however, we will focus on understanding radioactive decay and learn how to calculate the amount of radioactive substance that will remain after an integral number of half-lives have passed away.
Example: A patient is administered 18 mg of iodine-131. How much is left after 24 days? (The half-life of iodine-131 is 8 days.)
Begin by determining how many half-lives we are considering:
We are interested in the amount of iodine-131 left after 24 days.
After each 8 days, the amount remaining is cut in half. Thus, we are interested in 24/8 = 3 half-lives.
 
Next, figure out how much iodine-131 remaining after each half-life:
Initially (t = 0 days ) = 18 mg
1 half-life (t = 8 days )=18 mg /2 = 9 mg
2 half-lives (t = 8 + 8 = 16 days )= 9 mg/2 = 4.5 mg
3 half-lives (t = 16 + 8 = 24 days )= 4.5mg /2 = 2.25 mg
Thus, 2.25 mg of iodine-131 will remain after 24 days
Solve the following problems:
1. An isotope of cesium-137 has a half-life of 30 years. If 5.0 g of cesium137 decays over 60 years, how many grams will remain?
2. How many grams of californium-254 will remain after 363 days if we start with 64.0 grams of this substance? The half-life of californium-254 is 60.5 days.
3. 5.0 mg of radioactive nobelium-253 was removed from the reactor to be used in an experiment. It took 291 seconds (just under 5 minutes) to get the sample from the reactor to the laboratory. How many milligrams of nobelium-253 remained upon arrival to the laboratory? The half-life of nobelium-253 is 97 seconds.
in English·
1 Dec 2022

Derived Unit: Density

All the information I was given is in the picture please look at them thanks and make your work is not copied off of Google

Density, like volume, is a derived unit. It is a physical property of matter that is defined as the amount of mass per unit volume. For solids, the common unit is grams per cubic centimeter t(g/cm}^3). For gases and liquids, the common unit is grams per milliliter (g/mL).
 
The relationship between density, mass, and volume is very important. Knowing how to quickly solve for any of them will be very helpful throughout this course. Write the formula for density below or on a separate sheet of paper, and then solve for mass and volume.
 
1. Density =
 
2. Mass =
 
3. Volume =
 
Memorize the density formula and learn to derive the other two, or, if preferred, memorize all three of these formulas.
 
Water and octanol are immiscible. This means that if you add them together, they will not mix, blend, or form a solution. Thus, when you pour them both in a beaker, you will see two separate layers. If you pour octanol (density = 0.824 g/mL) and water (density = 1.00 g/mL) into the same beaker, which layer will be on the bottom? Why?
 
Can you think of another liquid that is immiscible with water? If poured into the same beaker, which layer do you think would be on the bottom? Please explain.
 
Let's say that you are performing an experiment with two clear, immiscible liquids in one graduated cylinder, but you do not know which layer is which. If you know that one layer is water, how could you determine which layer is water and which is the other liquid without looking up their densities?
 
 
 

 


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