Cathode rays consist of negatively charged particles called electrons. These electrons move away from cathode with very high speeds. These fast moving electrons collide with the molecules of the gas in the tube, split the molecule into atoms, and remove one or more electrons from the atoms.
Variations in the atomic properties of elements in any period are discussed below. Atomic number: In a period, the elements are arranged in the order of increasing atomic number. The atomic number increases by one unit atomic each element from left to right in a period.
All elements in a group generally show the same valence. From the values given in the above table, the valence of the main group elements is either equal to the number of valence electrons or 8-number of valence electrons.
We know that most rocks are hard; they have different colours-grey, brown, red, black or mixtures of colours. Some can be broken with the hand whereas some break only when they are hammered.
Graphite is a soft grayish-black greasy substance. The word ‘graphite’ comes from a Greek word meaning ‘to write’. The lead in our writing pencils is graphite mixed with clay. Graphite is also known as black lead or plumbago.
Diamond is the purest allotrope of carbon. In its purest form, diamond is a colourless, lustrous, crystalline solid. Diamonds are usually colored, some are tinged yellow, some blue, brown, green, pink and even black. This colour is due to some impurity. The grey or black variety of diamonds is known as carbonado and bort.
A suspension is a heterogeneous mixture in which very fine particles (10 -7 m) of a solid are dispersed in any medium (liquid or gas). Fine particles of the solid remain suspended in the medium.
A homogeneous-looking heterogeneous mixture in which particles having size between 10 -9 – 10-7 m are dispersed in a continuous medium is called a colloid.
Some of the most important properties of cathode rays are : Cathode rays travel in straight lines. That is why, cathode rays cast shadow of any solid object placed in their path. The path cathode rays travel is not affected by the position of the anode.
Some of the essential properties of Bases and Alkalis are 1. Bases are bitter to taste and soapy to touch. 2. Bases turn red litmus paper blue. and 3. Bases are characterised by the presence of hydroxyl (-OH) group.