lementsE

Basic Competence Students are able to to

explain the definition of element and compound.

What are elements?Elements are pure substances

(like hydrogen and oxygen) that can’t be split into simpler substances by chemical or physical means.Some common examples of elements are hydrogen, nitrogen, and carbon. In total, 118 elements have been observed. New elements are discovered from time to time by artificial nuclear reactions.

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Who disc vered elements?

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T SAs i have stated before, the Greek, Hindu, and Japanese came up with 4 main classical elements. In 1661 Robert Boyle showed that there were more than just 4 classical elements. The first modern list of chemical elements was given in Antoine Lavoisier's 1789 Elements of Chemistry, which contained thirty-three elements. In 1869, medeleev’s periodic table showed 66 elements.As the Years went by, more and more elements were discovered, up until now, there are 118 elements.

Robert Boyle Mendeleev

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2006 version :: 116 elementsThe periodic table of elements

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T S2008 version :: 118 elements

The periodic table of elements

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T SAtomic numberAs you’ve seen in the tables earlier,

there is a number next to the element. But what does this mean? The number is called the atomic number, which is determined by the number of protons in an element. For example, carbon

has 6 protons, so its atomic number is 6.Atomic mass

The atomic mass is the number of nucleons In the

atomic nucleus.

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T SClassical elementsMany ancient philosophies used

classical elements to explain patterns in nature

The Greek, Hindu, and Japanese shared the same classical

elements, which were Earth, Water, Air, Fire, and Aether

The fifth element, was used to describe that which was beyond

the material in this world.

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T SWhat do we use elements for?

On the other hand . . .

We use elements to construct

thousands of things. And

we need those things, such as steel

for our everyday

necessities. Without iron,

nickel, manganese, and many more, we would be

missing many types of

steel.

A laser, useable in manyareas of life.

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T SWhat do we use elements for?

On the other hand,

there are some

elements such as plutoniu

m, uranium,

and more

that are used to destroy.

Atomic Bomb 1945

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T S RadioactivityAgain, this all relates back to elements, as radioactivity would not be possible without elements.Benefits: Radioactivity is often used to diagnose and treat diseases. It can also produce energy for heat and electric power, and kill microorganisms that cause contamination and disease. Disadvantages: Is extremely harmful, and just a small dose will kill you.

This just proves my point about elements, that NOTHING could be possible without them.

Q&A

You can look but you better not touch

Plutonium. This emits alpha radiation. The radiation from even a small amount of plutonium gas will give you lung cancer.Mercury. This evaporates readily at room temperature, and is highly poisonous. It can cause brain damage.Lead. This stuff is put in the air by burning and fueling with leaded gasoline, and it appears in old paint. This can cause brain damage, especially for younger children.

What are some elements that are dangerous?Q:A

:

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T SIsotope Symbols

Example: H2O

What you see up there is an isotope symbol.

They make it easier to use them (elements) in chemical equations.

Note: All the Isotopes must be written in capital form. For example, the hydrogen in H2O Must be capitalized

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T SIsotope Symbols

H2O

The capitalized letter is used to abbreviate the original element. The number

however, the number is used to express the quantities of the element.

In this case, is we were to read this element, it would say 2 hydrogen, and 1 oxygen, which is water.

Reading the symbols

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