Structure of an atom

An atom consists of three fundamental particles: electrons, protons and neutrons. The electrons have negative charge; protons have positive charge while the neutrons have no charge. Structurally, an atom is divided into two parts: nucleus and extra nuclear portion. The nucleus is a tiny, heavy sphere which is present at the centre of an atom. The nucleus of an atom consists of protons and neutrons. Nucleus is positively charged due to the presence of protons in it. The diameter of nucleus ranges from 10-5 to 10–4 m.

The extra nuclear portion consists of negatively charged electrons which revolves around the positively charged nucleus in circular paths called orbits. In an atom, the number of electrons is always equal to that of protons. So, atoms are always electrically neutral.

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What is respiratory system?

The Respiratory system (or ventilatory system) is the biological system that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the...

What are enzymes?

Enzymes are complex chemical compounds made up of proteins which act as catalysts in our body i.e. the enzymes increase the rate of chemical reactions taking place in our body. For example, the digestion of food in our takes place in 4-5 hours due to action of...

What are surfactants?

The chemical compounds that work on the surface of a liquid and reduce its surface tension are called surfactants. In simple words we can say that surfactants are those chemicals that increase surface area of a liquid and enhance its wettability by reducing its...

Electrolytic refining of copper

We shall understand electrolytic refining of metals by taking the example of refining of copper. In case of copper, a thick block of impure copper is made anode and a thin block of pure metal is made cathode and copper sulphate solution is used as an electrolyte. On...

Froth flotation process

This method is used for concentration of sulphide ores of copper, lead and zinc. In this method, powdered ore is put in a tank full of water. And then, some Pine oil is added to it. In the tank the particles of sulphide ore are wetted by pine oil whereas the gangue...

What are metals?

Metals are the elements which can form positive ions by losing electrons. For example, Na is a metal because it can form positive ion (Na+) ion by losing an electron from its outermost shell. In the same way Iron, aluminium, copper, gold, silver, magnesium, potassium...

What is osmosis?

Osmosis is the phenomenon of water flow through a semi-permeable membrane that blocks the transport of salts or other solutes through it. Osmosis is a fundamental effect in all biological systems. It is applied to water purification and desalination, waste material...

What is photosynthesis?

Every living organism requires food to fulfill the requirement of energy for their various activities. Green plants are autotrophic in nature. So, they synthesize their food by a very important process called photosynthesis. The term ‘photosynthesis’ consists of two...

Reaction of sodium metal with water

Usually all metals react with water to produce metal oxide (or metal hydroxide) and hydrogen gas. But, all metals do not react with water at equal intensity. The metals which are very reactive can react even with cold water while the other metals react with hot water...

Work Done Against Gravity

Climbing stairs and lifting objects is work in both the scientific and everyday sense—it is work done against the gravitational force. When there is work, there is a transformation of energy. The work done against the gravitational force goes into an important form of...