Metals And Non - Metals - Notes, Chemistry | General Awareness & Knowledge - Bank Exams PDF Download

Metals & Non-Metals

Types of substances

• Elements
• Compounds

Elements

• Robert Boyle was the first scientist to use the term element in 1661.
• Antoine Laurent Lavoisier (1743-94), a French chemist, defined an element as a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Elements can be normally divided into:

• Metals,
• Mon-metals and
• Metalloids.

Physical Properties of Metal

• They have a lustre (shine).
• They have silvery-grey or golden-yellow colour.
• They conduct heat and electricity.
• They are ductile (can be drawn into wires).
• They are malleable (can be hammered into thin sheets).
• They are sonorous (make a ringing sound when hit).
  • Mercury is the only metal that is liquid at room temperature.

Chemical Properties of Metal

• Almost all metals combine with oxygen to form metal oxides.
• Most metal oxides are insoluble in water but some of these dissolve in water to form alkalis.
• Metals react with acids to give a salt and hydrogen gas
• Usually have 1-3 electrons in their outer shell.

Relative reactivity of metals

Physical Properties of Non-Metals

• Poor conductors of heat and electricity.
• Brittle - if a solid.
• Non-ductile.
• Do not possess metallic lustre.
• Transparent as a thin sheet.
• Solids, liquids or gases at room temperature.

Chemical Properties of Non-Metals

• Usually have 4-8 electrons in their outer shell.
• Gain or share valence electrons easily.
• Form oxides that are acidic
• Are good Oxidizing aqents
• Have higher electro- negativities

Metalloids

• Some elements have intermediate properties between those of metals and non-metals, they are called metalloids; examples are boron,  silicon, germanium etc.

COMPOUNDS

• A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.