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COMPOSITIONAL

FORMS

OF

MATTER

– all matter can be divided into three compositional classes

Elements

Compounds

Mixtures

A. Elements

– the basic units of all matter

– the building blocks

– you would no longer have an element

– elements cannot be broken down (or decomposed) chemically

To avoid writing out the entire name every time an element was used a “chemical shorthand” was developed

-there is one assigned to each element

each element is given a symbol known as the “Atomic Symbol”

also known as an abbreviated expression for an element

– usually an abbreviation of their names

-generally symbols are taken from the first letter of the name

-others must have two letters to distinguish them

Carbon and Chlorine

C and Cl

— 1st letter always capitalized

— 2nd letter always in lower case

-some are taken from their Latin names

Fe for Iron

Latin—Ferrum

K for Potassium

Latin—Kalium

!!!!!!!

LIST OF

REQUIRED ELEMENTS

!!!!!!!

Aluminum Al

Bromine Br

Calcium Ca

Carbon C

Chlorine Cl

Copper Cu

Hydrogen H

Iodine I

Iron Fe

Magnesium Mg

Mercury Hg

Nitrogen N

Oxygen O

Phosphorus P

Platinum Pt

Sodium Na

Sulfur S

Elements are divided into 2 general groups

1)

2)

Metals

Non-metals

1) Metals

Physical Properties

– Exception:

conduct heat and electricity

have a luster

some are ductile

some are malleable

most are solids

Mercury is a liquid

– metal elements exhibit a positive electrical charge

2) Non-metals

Physical Properties

not good conductors

usually brittle

not malleable

not ductile

some are solids, some liquids, some gases

– nonmetal elements exhibit a negative electrical

1 2 3 4 5 6 7 8

12

B. Compounds

substances composed of two or more elements combined chemically in definite proportions by mass

cannot be separated by physical means – only chemically

have both chemical and physical properties different from the constituent elements

***

Examples of Compounds:

salt

carbon dioxide

water

formaldehyde

NaCl

CO2

H2O

HCHO

C. Mixtures

a combination of two or more substances not chemically united and NOT in definite proportion by mass

may be separated by physical means

elements or compounds may be present in any proportion

– embalming fluid is a mixture

– blood

– milk

– air

– saltwater

– HCHO gas dissolved in water and “mixed” with all the other constituents

Other examples of Mixtures

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