Compounds

RELATED WORDS

  • Chemical compound
  • Electrochemical methods
  • Valency
  • Chemical formula
  • Covalent bonds
  • Ionic bond
  • Polar covalent bond

Definition of Compounds

A compound is a substance that is composed of two or more substances, chemically combined in a fixed proportion

More About Compounds

  • Elements react to form compounds
  • A compound is a chemical species that is formed when two or more atoms join together chemically, with covalent or ionic bonds
  • A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions
  • Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds
  • Pure chemical elements are not considered chemical compounds, even if they consist of molecules that contain only multiple atoms of a single element which are called diatomic molecules or polyatomic molecules
  • Elements in a compound are present in a definite proportion
  • Compounds have a definite set of properties
  • Elements that comprise a compound do not retain their original properties
  • For example, hydrogen (combustible and non-supportive of combustion) + oxygen (non-combustible and supportive of combustion) becomes water (non-combustible and non-supportive of combustion)
  • Valency is the number of hydrogen atoms that can combine with one atom of the element to form a compound
  • The physical and chemical properties of compounds differ from those of their constituent elements
  • The composition of each compound is always fixed
  • The compound formed has totally different properties
  • The constituents can be separated by chemical or electrochemical methods
  • A compound can only be created (either from elements or from other compounds or a combination of the two) by a chemical reaction
  • The ratio of each element in a compound is usually expressed by chemical formula
  • For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to an oxygen atom
  • The atoms within a compound can be held together by a variety of interactions, ranging from covalent bonds to electrostatic forces in ionic bond
  • H2O is held together by polar covalent bonds

Questions:

The written notation used to represent the number of atoms of each element in a compound is called the

    A) periodic table
    B) Chemical formula
    C) Electron configuration
    D) Valence numbers

Answer: B

2 .A mixtures in which one substance is uniformly distributed in another substance is called a (n)

    A) Metal
    B) Quark
    C) Solution
    D) Isotope

Answer: C

3) The state of matter that has no definite shape or volume is a (n)

    A) Solid
    B) Liquid
    c) Gas
    D) Plasma

Answer: C