Page 21 - eBook T2 eISBN2

MANUAL TITLE GOES HERE

4 scenarios occur when element expose or react to other elements or compounds. The

scenarios are:

1. Sometimes, when elements are mixed, the reaction occurs slowly. For example, when
iron is exposed to oxygen.

2. Sometimes, different elements can be mixed and no reaction occurs, so the elements
retain their individual identities.
3. Sometimes the reaction occurs rapidly such as when lithium is exposed to oxygen.
4. Sometimes, when an element is exposed to a compound, a reaction occurs in which
new compounds are formed. Example when pure elemental sodium is immersed in

liquid water.

Another fact about compound. Sometimes, when element react to others element, their states
are changed. For example, hydrogen (H) and oxygen (O). Both of elements are gases at room
temperature and normal atmospheric pressure. But when they combine into the familiar

compound known as water, each molecule of which contains two hydrogen atoms and one
oxygen atom (H 2 O), the resulting substance is a liquid at room temperature and normal
atmospheric pressure.

There is one group atoms of a few elements do not readily bond with other elements to form
compounds. These are called noble or inert gases: helium, neon, argon, krypton, xenon, and
radon. Certain elements readily combine with other elements to form compounds. Examples
are oxygen, chlorine, and fluorine.

Types of Compounds

Metallic compounds. A metallic compound is a compound that contains one or more metal
elements bonded to another element. Typically, the metal atom acts as the cation in the
compound and is bonded to a nonmetallic anion or an ionic group. Because it has a positive

charge, the metal element symbol is listed first in the chemical formula.

Most metals do not occur in their natural state. They are often found as compounds such as
metal oxides, sulfides and halides.

• Aluminum oxide is the main metal compound present in the ore known as bauxite.

• Iron pyrites or ‘fool’s gold’ is mainly iron sulfide.

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