Compounds are depicted by their chemical formula which follows the Hill system wherein carbon atoms are listed first, followed by hydrogen atoms after which elements are listed in alphabetical order. Sometimes foreign elements are trapped inside crystal structure of compounds giving them a non homogeneous structure. Most compounds can exist as solids (low enough temperatures) and can be decomposed by the application of heat. Valency is defined as the number of hydrogen atoms required that can combine with an atom of the element forming the compound. The combining of elements is facilitated by their valency. The elements in a compound do not always retain their original properties and cannot be separated by physical means. For example, 1 atom of sodium (Na) combines with 1 atom of chlorine (Cl) to form one molecule of sodium chloride (NaCl) compound. carbon binds in a tetrahedron to form diamond and layers of hexagons of carbon forms graphite.Ĭompounds are composed of different elements in a fixed proportion. Allotropes – atoms of an element can form bonds with each other in more than one way leading to difference in their chemical properties.carbon has three isotopes, Carbon - 12, Carbon -13 and Carbon - 14. Thus isotopes have similar chemical properties (due to same number of protons) but different nuclear properties (due to different number of neutrons). Naturally occurring elements have more than one stable isotope. Isotopes – isotopes of an element have the same number of protons in their nucleus but differ in the number of neutrons.Isotopes of the same elements differ in their atomic masses. Atomic Mass – the letter A indicates the atomic mass of the element which is the total number of protons and neutrons in the nucleus of an atom of the element.Number of protons is also indicative of electric charge or number of electrons present in the nucleus which determines chemical properties of the element. carbon has 6 protons in its nucleus and for Carbon, Z = 6. Atomic number – the atomic number is denoted by the letter Z and is the number of protons present in the nucleus of the atom of element.In the Periodic Table, elements are arranged according to their atomic number and they are grouped according to similar chemical properties and are depicted by their symbols. Hydrogen (H), Oxygen (O), Sodium (Na), Chlorine (Cl), Carbon (C), Iron (Fe), copper (Cu), silver (Ag), and gold (Au) are examples of elements.Įlements are distinguished by their name, symbol, atomic number, melting point, boiling point, density and ionization energies. Water (H2O), Sodium chloride (NaCl), Sodium bicarbonate (NaHCO3) and Hydrochloric acid (HCl) are examples of compounds. Can be classified as metal, non-metal or metalloid. There are about 117 elements that have been observed. Compounds are classified into molecular compounds, ionic compounds, intermetallic compounds and complexes. Each atom has the same atomic number i.e., the same number of protons in their nucleus.Ī compound can be separated into simpler substances by chemical methods/reactions.Įlements cannot be broken down into simpler substances by chemical reactions.Ī compound is represented using its chemical formula that represents the symbols of its constituent elements and the number of atoms of each element in one molecule of the compound.Ī huge, virtually limitless, number of chemical compounds can be created. Elements that compose the compound are chemically combined.Įlements contain only one type of atom. Comparison chart Compound versus Element comparison chartĪ compound contains atoms of different elements chemically combined together in a fixed ratio.Īn element is a pure chemical substance made of same type of atom.Ĭompounds contain different elements in a fixed ratio arranged in a defined manner through chemical bonds.
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