Isotopes

Isotopes

What is an isotope?

The isotopes are atoms whose their nucleus have the same number of protons but different number of neutrons, this means their atomic number is the same but their atomic mass is different. Not all the atoms of the same element are identical and each of these varies in a different isotopes.

Discoverement:

The existence of the isotopes was discovered by F. Soddy in 1911. Soddy noticed the similarities between their chemical properties
Most of the natural elements are formed by several isotopes that can only be separated by physical procedures.

Classification:

We can classify isotopes as stables, that can exist around 3 billion years and unstables or radioactives, which emit radiation. These are used in obtaining electrical energy through nuclear fission reactions, in measuring apparatus, etc.

The atomic mass of an element in the periodic table is the average of the isotopes that has been discovered in a natural way.

Types:

There are two types of isotopes: the light isotopes usually have less neutrons that protons if they are not the same; and the heavy isotopes, they usually have more neutrons than protons.

You can find isotopes with a only a few or a lot of neutrons, this atoms can only exist for a while, but they are unstable. These are radioactive: their nucleus change or they desintegrate emitting radiations.

How are they representated?
There are two ways of representing them: according to scientific notation and according to symbolic notation.

Scientific Notation: The isotopes are identified by the name of the  element followed by the number of protons and neutrons of the isotope.
Ex: U-234, U-235 and U-238


Symbolic Notation: The number of protons and neutrons is denoted as the superscript prefix of the chemical symbol.
Ex: ²³⁴U, ²³⁵U  and ²³⁸U

Hope you have learn with our blog of isotopes.

Juan Sebastian Olarte- Gabriel Rios 8-40

Atomic Theory and John Dalton

Atomic Theory

The universe, where did all of that came from? 

In this post we are going to show you The Atomic Theory and how it explain the origins of the universe and matter

The Theory:

It says that every matter in the universe is made by a very small particle called the atom, the atom is indivisible and the smallest unit in the universe, making them the blocks of builiding of the universe. The atom is made by three subatomical parts: Electrons(Negative), Protons(Positive) and Neutrons(No charge) which the protons number on an atom of a element says the atomic number of that element.
 Its origin came from -400 B.C when Democritus said that everything on the universe was indivisible until the atom, the problem of this theory is that he didnt have any proof, so Aristotle dismiss it saying that such particle couldnt exist; adding that he believed that all the matter was made by four elements: water, fire, air, and dirt. The theory was forgot until some centuries later.

John Dalton:

After many years, John Dalton return to the atomic theory, probably one of the most important works on chemistry in 1808.

In this postulated that:

1. All matter consists of indivisible particles called atoms.
2. Atoms of the same element are similar in shape and mass, but different from the atoms of other elements.
3. Atoms cannot be created or destroyed.
4. Atoms of different elements may combine with each other in a whole number ratios to form compound atoms.
5. Atoms of same element can combine in more than one ratio to form two or more compounds.
6. The atom is the smallest unit of matter that can take part in a chemical reaction.

Daltons Symbols:

Dalton believed that every element was made by a class of atoms, that was different in properties to the atoms of other elements, thats why every elemtn is different from each other. So he  put a symbol for every known symbol to difference them, this symbols helped to reach todays elements symbols

Mental Map:

You can see the mental map of this theme in the link below

https://drive.google.com/file/d/0B47_dOPq-NKpMkotY0FIeWZZN3c/view

Debatable questions:

If you had live in year-400 B.C would you have believed Democritus? Why?

Do you think we can find even a smallest unit than atoms and its parts?

The Atomic theory is the most believable theory? Why?

Juan Sebastian Olarte-Gabriel Rios 8-40

Introduction

INTRODUCTION

This blog is from Chemistry/Physics of eighth grade of the Saint Viator School , taught by the professor Eliecer Covian.

Here we will be writing what we have seen in class.

Juan Sebastian Olarte-Gabriel Rios 8-40