Binary Compounds Type I

Hi everyone

Here is a head scrambler for you, which is naming compounds. Today, I will show you how to name two elements together; in in the scientific language we called this binary compounds type I. Binary compounds type I is about connecting elements that can form only one type of cations with elements that form anions. The rules are simple,

1.     The cation is always named first, and the anion second.

2.     The cation is name after the element.

3.     The anion is name by taking the first part of the element name and adding –ide.

Here are common simple cations and anions.

Examples

What is the name of Li  - lithium (+1 charge) and F – fluorine (-1 charge)?

Li is a cation with charge +1, and F is an anion with charge -1.

Li⁺+F^- = LiF

The name of the compounds is lithium fluoride

What is the name of K potassium and I iodine?

K is a cation with charge +1, and I is an anion with charge -1.

K⁺+I^- = KI

So the name is potassium iodide

As you see from these examples, the charges on cations and anions are the same +1 and -1, to give the zero net (because -1 +1 = 0), but what happen it the charges are different like +2 and -1? Well, we have to balance them to zero, but the naming rules are the same.

Examples

What is the name of Mg magnesium  (+2 charges) and Br bromine (-1 charge)?

+2            -1

Mg + Br= MgBr₂     

Mg has +2 charges and bromine -1 charge. To have zero net, we have to multiply -1 Br times 2 to have -2 (because +2 and – 2 is zero) therefore we have Br₂

The name of the compounds is magnesium bromide

What is the name of Na sodium (+1 charge) and O oxygen ( -2 charges)?

The name is sodium oxide, but the formula is

 

+1         -2

Na + O= Na2O 

Ions, Cations, and Anions

          Today, I will discuss the differences between ions, cations, and anions. From the last post about the structure of atoms, we know that an atom has the same number of electrons (negative charge) and protons (positive charge) to make the atom in an exact balance (neutral atom). What happens when an atom has extra electron or missing electron? The atoms are called ions.

So, when you are missing an electron or two, you have a positive charge called cation. When you have an extra electron or two, you have a negative charge called anion.

An example of creating cation.

A neutral lithium (Li) has 3 protons and 3 electrons, and it is missing an electron. Then we have 3 protons and 2 electrons. So lithium loses one electron to become a 1+cation.

An example of creating anion.

                                        

A neutral chlorine Cl has 17 protons and 17 electrons, and it is gaining one electron. Then we have 17 protons and 18 electrons. So, chlorine gained one electron to become a 1- anion.

The Structure of the Atom

Hi everyone 

Last time I discussed the organization of the periodic table. As we know the periodic table contains 118 elements. Each element has a name, symbol, weight, and atomic number. So, all matter (everything what is around us) is made of elements (atoms). An atom is like a tiny solar system. In the center of the atom is the nucleus, which is a group of protons and neurons. The protons have a positive electric charge while the neutrons are electrically neutral. The nucleus makes up almost all of an atom’s mass or weight. Spinning at fantastic speeds around the nucleus are smaller and lighter particles called electrons that have a negative electric charge.  An atom has the same number of electrons (negative charge) and protons (positive charge) to make the atom in an exact balance—it has zero net charge.

For example

A Carbon C atom has six protons in its nucleus and six electrons outside its nucleus, which mean the element has zero net charge.

Introduction to the Periodic Table

In any classroom where chemistry is taught there is a big chart called the periodic table, and we also have one in my classroom’s wall. This week the real chemistry began, and I learned the organization of chemical elements. The periodic table has 118 boxes, which contains a symbol and number of the element. The boxes are place in horizontal order of increasing number (they are called a proton or atomic number). Also, the elements are place in vertical way called groups, which mean they have similar chemical properties. The first group has the name alkali metals; the second group is called alkaline earth metals. Next we have couples groups of transition metals, metalloids group, chalcogens, halogens, and noble gases group. In an easier way, we can divide all the elements on metal and not metal.

Below there are two pictures.

1. The elements classified as metals and as nonmetals.

2. The more specified organization of the elements

Do you know where you come from? because science does

Hi guys,

Imagine a person that went for vacation to a different state from where there home is. During the vacation the person was attack and robbed. He/she was hit in the head, and lost their memory. The person doesn’t remember what happened and has no form of identification. Do you know how to find out where the person might be from?

Recent research indicates that the relative amounts of the isotopes of hydrogen and oxygen in a person’s hair indicate in which part of the United States a person lives. James Ehleringer, a chemist at the University of Utah in Salt Lake City, observes that the concentrations of hydrogen-2 and oxygen -18 in drinking water vary significantly from region to region in the United States. Ehleringer and his colleagues collected hair samples from barbershops in 65 cities and 18 states. Their analyses showed that 86% of the variations in the hydrogen and oxygen isotopes in the hair samples result from the isotopic composition of the local water. Based on their result, the group was able to develop estimates of the isotopic signature of peoples’ hair from various region of the country. Although this method cannot be used to find out the person's physical address, it can give a general region. This method might be helpful for the amnesia person where to look for his/her family.  

Those maps show concentrations of hydrogen-2(top) and    oxygen 18(bottom). Red represents the highest concentration, and blue represents the lowest concentration of each isotope.

Rounding Off Numbers and Significant Figures

Nowadays everyone have a calculator that helps to calculate large numbers, but large numbers are difficult to use in chemical tasks. So, it is very important to know how to round the answer off correctly.

We have two rules for rounding off numbers.

If the digit to be removed

is less than 5 (that is 1,2,3,4), the previous digit stays the same.

For example   2.334 the last digit is 4, which is less than 5, so the previous number 3 will stay the same. The answer is 2.33

           

            is equal to or greater than 5 (that is 5,6,7,8,9), the previous digit is increased by 1.

For example   2.336 the last digit is 6, which is greater than 5, so the previous number 3 will increase by 1. The answer is 2.34

Second part of my post is significant figures.

They are 3 rules that we have to understand to know how to count significant figures.

I.          Leading zeros are never significant.

For example

3 4 5 6 0 0 0 0 0, this number has 4 significant numbers (we don’t

        1   2  3  4                    count the zeros)

II.         Captive zeros are always significant numbers.

For example  

4 6 0 0 2 1, this number has 6 significant numbers

1  2   3  4   5  6                                 

III.       Trailing zeros are sometimes significant figures. This part makes some people confused. 

            I will try to explain this in very simple way.

            The trailing zeros are significant only if the number is written with a decimal point.

For example

3 4. 5 6 0 0 0  this number has 7 significant numbers because it has a decimal   

1   2   3  4   5  6  7   point between 4 and 5, which means the zeros are significant.

 Without the decimal point (3456000), we have only 4 significant numbers.

Now, let’s put all the information together by solving problems.

Round 53.7285 to four significant figures. The answer is 53.73 ( four s.f)

        

 This number has 6 significant figures, but they ask us to round the number to four significant figures. The fifth digit is 8, which is greater than 5(it is the second rule for rounding off numbers) so the previous number 2 will increase by 1, giving us 3.

Round 23.50343 to three significant figures. The answer is 23.5

           

This number has 7 significant figures, but they ask us to round the number to three significant figures. Look on the fourth digit, which is 0 less than 5, so the previous number 5 will stay the same (this is the first rule for rounding off numbers)