Skip to main content

Atomic Mass

Atomic Mass

Introduction

  • Atom is made up of 3 sub-atomic particles i.e. electron, proton & neutron. Every object that exists in 3-D has mass. Atom to have mass and the  mass of an atom is very small.
  • The mass of an atom is calculated by using sophisticated techniques like mass spectrometry.
  • But in the 19th century, scientists could easily determine the mass of one atom relative to another atom.
  • Initially, the scientist took 1/16 of the mass of a naturally occurring oxygen.
  • The main reason for taking oxygen was that oxygen could react with a large number of elements, and by using Oxygen-16 the masses of many elements came as whole numbers.
  • In 1961 carbon-12 was taken as the standard and had been agreed upon.





Relative Atomic Mass

The average mass of an atom compared to the 1/12th mass of a Carbon-12 atom.

Atomic Mass Unit

  • Its is a mass unit.
  • 1 amu is defined as a mass which is exactly equal to one-twelfth the mass of one carbon-12.
  • 1amu = 1.66056*10^-24 g
  • amu is usually replaced by 'u' which is known as unified mass.



Elements and Their Atomic Masses

Hydrogen     = 1u
Helium         = 4u
Carbon         = 12u
Nitrogen      =  14u
Oxygen        = 16u
Sodium        = 23u
Magnesium  = 24u
Sulphur        = 32u
Chlorine      = 35.5u
Potassium    = 39u
Calcium       = 40u
Iron             = 55.8u

You Might Also Like


Labels:

Comments

  1. TEACHERLOOKUP. COM19 June 2019 at 23:27

    This information is meaningful and magnificent which you have shared here about the Atomic Mass Number. I am impressed by the details that you have shared in this post and It reveals how nicely you understand this subject. I would like to thanks for sharing this article here.

    ReplyDelete

Post a Comment

Popular Posts

Anode Ray Experiment

→Anode ray experiment was conducted by E Goldstein. →These rays are also known as canal rays. →This experiment helped in the discovery of the proton. Apparatus Used A discharge tube  was taken in which there were 2 electrodes i.e. Anode(+ve) and the cathode (-ve). The tube was filled with an inert gas. A perforated or porous cathode was used. A layer of zinc sulphide was placed at the back of the cathode. There was a vacuum pump in the tube. High voltage (5000v-10000v) was allowed to flow through the system. It was observed that when the gas was at 1atm(atmospheric pressure ) no change was seen in the tube.  When the   pressure   was decreased inside the tube, a glow could be seen at the back side of the cathode.
2 comments
Read more

High School Pedia

It is an initiative by some students to spread the light of knowledge to everyone and everywhere. It was started in the year 2015 and has grown rapidly in the past few months. By the means of this website, we try to provide information on every topic that we can reach up to. You can find different articles on this website. All these articles are written in simple language so that everyone can understand it and learn from it. We at High School Pedia believe in creative learning and this is the reason why we add our own edited graphical representations in every article. Once a very learned man said, “Knowledge increases by not keeping it to yourself but by sharing it with others”. And we follow the same motto “Share to Learn”. The team of High School Pedia tries its best to provide you with the best and original content. Unlike many other websites, High School Pedia is famous for its original and inspiring content.
2 comments
Read more

Animal and Plant Cells

 Cells Cells are the basic functional, biological and structural unit of life. The word cell is a Latin word meaning ‘small room’. Cells are also known as building blocks of life.  The branch of science that deals with the form, structure, and composition of a cell is known as Cytology. All organisms around us are made up of cells. Bacteria, ameba, paramecium, algae, fungi, plants and animals are made up of cells.  Cells together form tissues. And tissue together makes an organ. History Of Cell The cell was discovered by Robert Hooke in 1665. He assembled a simple microscope and observed a very thin slice of cork under his primitive microscope. The cork was obtained from the outer covering of a tree called bark. Robert Hooke observed many little-partitioned boxes or compartments in the cork slice. These boxes appeared like a honey-comb. He termed these boxes as the cell. He also noticed that one box was separated from another by a wa...
23 comments
Read more

Permutation and Combination

Permutation and Combination Hey guys, I am back with one more interesting mathematics topic. And I am pretty sure that you guys would find it interesting too because many of you must have faced problems regarding these arrangements. Although if you were not able to solve them at that moment of time I am sure after completing this article you would solve the problem in minutes or even seconds. WHAT IS THE DIFFERENCE ?? Many people get confused between these two terms permutation and combination. They both have almost similar use but have a vast difference in their meaning. You may think that both of them mean arranging entities, then what is the difference ?? For making it easy we will take an example, lets say I have four friends : Arya, Bhavesh, Chirayu and Dhruv. So if I arrange them like Arya, Bhavesh, Chirayu and Dhruv or Dhruv, Chirayu, Bhavesh and Arya, it will make no difference in combinations but if you check them according to permutation they will be different. As ...
5 comments
Read more

Important Mathematical Constants!

Important Mathematical Constants Mathematical constants are those numbers that are special and interesting because they come up in the various fields of mathematics like geometry, calculus etc. These mathematical constants are usually named after the person who discovered it and they are represented by a symbol that is usually picked up from the Greek alphabet. Mathematical constants are by definition very important. In this article we will take a look at certain mathematical constants that are more commonplace than others. 1.       π (pi) or Archimedes constant (~3.14159):   π is defined as the ratio of the circumference of a circle to its diameter. This is probably the most popular mathematical constant. So π is the circumference of the circle whose diameter is 1 unit. You might have seen it popping up when calculating the area of a circle (πr 2 ) or the circumference of a circle (2πr). It has many uses throughout mathematics from calcula...
4 comments
Read more

Catalysts

Catalysts When we hear the word catalyst, the first thing that comes to mind is the game “Mirror’s Edge Catalyst”. But actually, catalysts are chemical substances that speed up the process of a chemical reaction but do not used up in the process of speeding up. The process of using catalysts to speed up chemical processes is called catalysis. Some examples are: Ø Hydrogen peroxide decomposes to form water and oxygen. 2H2O2 à 2H2O + O2 But in the presence of manganese dioxide (MnO2) the process is sped up and happens a lot faster. Ø Cars use a catalytic converter to convert carbon monoxide to carbon dioxide. These contain Platinum to speed up the process and keep the car’s system getting backed up. Ø Ammonia synthesis also uses Iron as a catalyst Catalysts work by reacting with a reactant. This is called a catalytic action. The product of the catalytic action is a chemical intermediate, which can react with the other reactant at a faster pace and give...
Post a Comment
Read more

Autonomous Cars

The Problem with Self-Driving Cars Every year, so many people die in car accidents, most of them caused because of the driver's negligence. Exorbitant amounts of money are spent just to fund awareness campaigns and stop people from “drinking and driving”. All of this after the fact that the technology for self-driving cars is in the last stages of development. Why are self-driving cars not the next big thing yet? Companies like Tesla, Uber and heck, even Google are racing to be the next innovator of autonomous cars. “This is stupid… Obviously, the cars are expensive.” See that’s the point, these cars are not ridiculously expensive (at least not for people who own an iPhone X). “Well then we obviously don’t have the requisite technology” That is partially true but trust me, the cars are way closer technology-wise than you may think. The biggest problem with autonomous cars is (insert drumroll) “A Moral Dilemma”. Disappointed? Just hear me out. Imagine ...
Post a Comment
Read more