The elements that do not occur naturally on Earth are the synthetic products of man-made nuclear reactions. Hydrogen and helium are by far the most abundant elements in the universe. The remainder is dark matter, a mysterious substance that is not composed of chemical elements. Dark matter lacks protons, neutrons, or electrons. Pure samples of isolated elements are uncommon in nature. Carbon is also commonly found in the form of coal, graphite, and diamonds.
The noble gases e. Still, most of these elements are found in mixtures. When two distinct elements are chemically combined—i. Most elements on Earth bond with other elements to form chemical compounds, such as sodium Na and Chloride Cl , which combine to form table salt NaCl.
Water is another example of a chemical compound. The two or more component elements of a compound can be separated through chemical reactions. Chemical compounds have a unique and defined structure, which consists of a fixed ratio of atoms held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be:.
Pure chemical elements are not considered chemical compounds, even if they consist of diatomic or polyatomic molecules molecules that contain only multiple atoms of a single element, such as H 2 or S 8. Compounds include more than one kind of atom. Elements are classified depending on their properties, and compounds are ranked based on their bond type. Symbols represent elements, and compounds are defined by their chemical formulas. Their atomic number identifies elements. Their atomic ratio separates compounds.
Chemical reactions cannot break down elements, but they can break down the compounds. This is the main difference between compound and element. Some other factors differentiate between element and compound, such as total numbers, properties, composition, examples, etc.
The periodic table includes elements. The compounds are uncountable. The elements have the properties of their parent atom. The compounds do not have specific properties, and the properties vary with the bond type.
Elements are formed with the same types of atoms. For example, we are considering oxygen O 2. Oxygen is formed with two oxygen O atoms of the same kind, atomic number and properties.
Compounds are constructed with more than one type of atom. For example, we are taking water H 2 O. Water is formed with two Hydrogen H and one Oxygen O atoms. Water is constructed by the covalent bond between H and O atoms. That is why water has various properties.
Write the Bond Type of the Given Compounds —. An element is a pure chemical substance made of same type of atom. Composition Compounds contain different elements in a fixed ratio arranged in a defined manner through chemical bonds. They contain only one type of molecule. Elements that compose the compound are chemically combined. Elements contain only one type of atom. Each atom has the same atomic number i. Elements cannot be broken down into simpler substances by chemical reactions.
Representation A 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.
An element is represented using symbols. Types A huge, virtually limitless, number of chemical compounds can be created. Compounds are classified into molecular compounds, ionic compounds, intermetallic compounds and complexes. There are about elements that have been observed. Can be classified as metal, non-metal or metalloid. Differences in Properties Elements are distinguished by their name, symbol, atomic number, melting point, boiling point, density and ionization energies.
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. For e. Number of protons is also indicative of electric charge or number of electrons present in the nucleus which determines chemical properties of the element.
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. Isotopes of the same elements differ in their atomic masses. Isotopes — isotopes of an element have the same number of protons in their nucleus but differ in the number of neutrons.
Naturally occurring elements have more than one stable isotope. Thus isotopes have similar chemical properties due to same number of protons but different nuclear properties due to different number of neutrons. Allotropes — atoms of an element can form bonds with each other in more than one way leading to difference in their chemical properties.
Visualizing the Differences This picture shows the differences between elements and compounds at an atomic level.
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