about 30 elements'

> Noble gases, some metals, carbon, silicon etc. have only one atom in their molecules. These are called monatomic molecules. Some elements have two atoms in their molecules. These are called diatomic molecules e.g., hydrogen (H 2 ), oxygen (O 2 ), nitrogen (N 2 ), chlorine (Cl 2 ), etc. ..

"An element is a pure substance which is made up of only one kind of atoms having the same atomic number." "The smallest particle of an element is the atom which, has all the properties of that element." "An element cannot be broke..

Identify the missing element in the table. => 28 or 30 or 26 or 24..

Introduction - At the turn of the nineteenth century, about 30 elements were known. 50 years later by the 1850s, scientists had discovered sixty three chemical elements and the numbers kept increasing. With the discovery and study of more and more elements an..

In potassium (Z=19) and calcium (Z=20), electrons enter the 4s-orbitals in accordance with the fact that 4s-orbital is slightly lower in energy than 3d-orbital. With scandium (Z=21), 3d-subshell comes into use and from scandium to zinc, this subshell is gradually filled up. The electronic configura..

>The longest-lived isotope of fermium ..

Element Symbol Relative Atomic Mass Element Symbol Relative Atomic Mass Aluminium Al 26.98 Magnesium Mg 24.31 Bromine Br 79.90 Mercury Hg 200.50 Calcium Ca 40.08 Nitrogen N 14.01 Carbon C 12.01 Oxygen O 15.99 Chlorine Cl 35.45 Pho..

1 (k.J mo1 -1 ) 1402 1012 947 834 703 IE 2 2856 1903 1798 1594 1610 IE 3 4577 2910 2736 2443 2446 Electronegativity 30 2.1 2.0 1.9 1.9 Melting point (K) 63 317.1 1089 904 544.4 Boiling point (K) 77 553.5 888 ..

At the turn of the nineteenth century, about 30 elements were known. 50 years later by the 1850s, scientists had discovered sixty three chemical elements and the numbers kept increasing. With the discovery and study of more and more elements and their compou..

The symbol of an element is a short way of representing an element. Symbols can be formed as follows: 1) By using the first letter of the English name of the element. Hydrogen H Phosphorus P Oxygen O Sulphur S 2) By using the fi..