elements and compounds
A compound is a combination of two or more elements. An element is a pure substance that cannot be separated into simpler substances by physical or chemical means
the difference between a compound and an element is that the compound is a combination and the element is a pure substance. Most of the matter in the univers exist as compound
Separating a compound, often requires external energy, such as heat or electricity
Matter
Pure substances
Elements
Compounds
Mixtures
Heterogeneos
Homogeneous
The perioodic table is organized into a grid of horizontal rows called periods, and vertical columns called groups. There are 103 elements in total, from wich 92 can be find in the nature, the other 11 are created artificialy
Law of definite proportions
the law of define proportions states that in a elements, not depending in the amount of the element, ther will be always the same component in the elemets
percent by mass (%)=
mass of element/mass of compound
X 100