Ionic and Covalent Bonds

 

Ionic bonds are formed from metals and nonmetals or a metal and a polyatomic ions which are typically made of nonmetals.

Covalent bonds are formed from two or more nonmetals

If you look at the periodic table you can locate this stairstep. Elements to the left of the stair step are metals except for hydrogen which is a nonmetal and to the right are nonmetals.

Let's look at some examples of ionic bonds.

Sodium chloride

NaCl

If you look at the periodic table you will see sodium is on the left so it is a metal, and chlorine is on the right, so it's a nonmetal. A metal and a nonmetal results in an Ionic bond.

Potassium bromide (KBr)

It’s made of potassium and bromide. Potassium is on the left so it's a metal, and bromide is on the right so it's a nonmetal.

What about this compound ? It has more than two elements like the previous example.

Lithium Nitrate

LiNO3

This compound is made up of lithium which is a metal and two nonmetals bonded together called nitrate, which is a polyatomic ion that has elements bonded together but act as one.

This is a covalent bond because it’s a metal and nonmetals bonding together.

What about sulfur dioxide?

It’s made of sulfur and oxygen which are both nonmetals so it is a covalent bond

How about water which has a formula of H2O?

It’s made of hydrogen and oxygen which are both nonmetals so it’s a covalent bond Remember although hydrogen is on the left it’s an exception and is a nonmetal.

How are the atoms held together in these different compounds?

Let’s look at covalent bonds first.

Compounds with covalent bonds are held together because they are sharing electrons.

Let’s look at water which illustrated above.

They are connected because they are sharing electrons and this holds the compound together.

Now let’s look at sodium chloride which is held together by an ionic bond.

Chlorine wants one electron so takes one electron from sodium. As a result sodium and chlorine become ions which is an element with a positive or a  negative charge. 

The sodium becomes a positively charged ion called a cation and the chlorine becomes a negatively charged ion called an anion.

Now you have a negative and positive charge attracted to one another and this bonds the elements together.

So how can you remember the difference?

In order to remember covalent, I think of co-presidents which share the power or cohabitate  where you share a space.

In order to remember ionic, I think "I want your electron" which results in gaining and losing an electron which results in creating an ion.

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Heron's Formula

Heron's formula is a formula that gives the area of a triangle given the lengths of its three sides. It is named after Heron of Alexandria, a Greek mathematician who lived in the 1st century AD. The formula is: A = sqrt(s(s-a)(s-b)(s-c)) where: A is the area of the triangle s is the semiperimeter of the triangle, which is half the sum of the lengths of the three sides a, b, and c are the lengths of the three sides of the triangle

Heron's formula can be derived using trigonometry or geometry. It is a powerful formula that can be used to find the area of any triangle, regardless of its shape or size.

In the video I work through an example problem that will show you how to use Heron's formula.

I hope it helps.

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Rules for rounding Numbers

 If you need to round 65.44 to the tenth place, do you round the 4 to 5 or leave it as is?

You can use this simple statement to help with this.

Four or less let is rest

Five or more raise the score

So with this example problem you look at the 100th place and it is 4 so you keep the 10th place the same.

65.44 = 65.4

Now let's round 76.568 to the 100th place.

Look at the 1000th place, it is 8 which is five or more so it becomes ....

76.568 = 76.57

Round 62.5789 to the 10ths

Look at the 100th, and it is 7 so five or more raise the score so 62.5789 rounded to the 10th is 62.6

You may enjoy this playlist of our Math shorts

Math Shorts

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Multiply Positive and Negative Numbers

 

When you multiply two negative numbers, is the answer a negative or positive number?

Follow these two simple rules in order to multiply properly.

1. When both signs are the same, the answer will be positive.

2. When one sign is positive, and one is negative, the answer will be negative.

For example,

-5 x -4 = 20

-5 x 4 = 20

3 x 6 = 18

-4 x - = 24

This same rule applies to division of two integers.

You may enjoy this playlist of my Math shorts over many Math topics.

Math shorts

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Rationalize the Denominator

Many times you may need to rationalize the denominator which means there will not be an irrational number as the denominator.

Rationalizing the denominator involves rewriting a fraction so that the denominator is a rational number. This can be done by multiplying both the numerator and denominator of the fraction by a suitable expression.

For example, to rationalize the denominator of the fraction 1/√2, we can multiply both the numerator and denominator by √2: 1/√2 * √2/√2 = √2/√4 = √2/2

Now the denominator is a rational number, 2.

Let's rationalize the denominator of 1/√3

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The Outer Planets-Jovian Planets

The Outer Planets which are also called the Gas Giants include Jupiter, Saturn, Uranus, and Neptune. These planets are also called the Jovian Planets. The term Jovian means Jupiter like. The Jovian planets, also known as gas giants, are the four largest planets in the Solar System: Jupiter, Saturn, Uranus, and Neptune. They are all composed primarily of hydrogen and helium, and have thick atmospheres and no solid surfaces.

Jupiter

Largest planet in the Solar System Has a thick atmosphere with a Great Red Spot Has 79 known moons

Saturn Second largest planet in the Solar System Has a thick atmosphere with a hexagonal-shaped polar vortex Has 62 known moons

Uranus Third largest planet in the Solar System Has a thick atmosphere with a unique tilt Has 27 known moons

Neptune Fourth largest planet in the Solar System Has a thick atmosphere with a Great Dark Spot Has 14 known moons

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Properties of Nonmetals

Nonmetals are found on the right of the periodic table and tend to gain electrons.

There are 17 nonmetals Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Chlorine Argon Phosphorus Sulfur Selenium Bromine Krypton

They range from brittle solids to gasses at room temperature. Because their outer shells are filled with electrons they tend to gain electrons.

They share some of these properties.

Nonmetals share these properties

• Low density

• Poor conductors of heat and electricity

• Not malleable or ductile

• Brittle solids or gasses at room temperature

• React with metals to form salts

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