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
