CLASSIFICATION OF MATTER IN CHEMISTRY Chemistry teacher team of SMAN 1 Tarakan Based on Prof. Effendy material

AFTER LEARNING THIS TOPIC, YOU MUST BE ABLE TO : understand the classification of matter. understand the difference of element, mixture and compound. differentiate between physical and chemical properties of substances. differentiate between physical and chemical changes of matter.

Classification of matter

Heterogeneous mixture: A mixture with a composition that varies from point to point Examples: mayonnaise chocolate chip cookies concrete

Homogeneous mixture: A mixture with a composition that doesn’t vary from point to point Homogeneous mixture is also called solution Examples: Mixture of water and alcohol Mixture of table salt and water Mixture of sugar and water

Separation of mixtures Mixture of iron and sulfur may be separated by using a magnet

Mixture of two liquids with different boiling points such as mixture of water and alcohol may be separated by distillation

Mixture of colored substances such as the components of a green ink may be separated by column chromatography

Mixture of two crystalline substances from a solution such as barium chromate, BaCrO4, and strontium chromate, SrCrO4, may be separated by fractional crystallization. Barium chromate is less soluble in water than strontium chromate. Barium chromate crystallizes before strontium chromate.

Most of substances in the world are compounds. What is compound Most of substances in the world are compounds. What is compound? Compound is a pure substance that is formed when atoms of two or more different elements combine and create a new material with properties completely unlike those of its constituent elements.

Formation of a compound from its elements involves a chemical change, called chemical reaction

For example: Sodium (a soft, silvery metal) combines with chlorine (a toxic, yellow-green gas) to give sodium chloride (salty table salt)

Hydrogen (colorless gas) combines with oxygen (colorless gas) to give water (colorless liquid).

In the compound, the elements no longer have the same properties they had before they were combined. The properties of H2O is different from the properties of H2 and O2.

A compound is written by giving its chemical formula, which lists the symbols of the individual constituent elements and indicates the number of atoms of each element with subscript. Chemical formula of compound Constituent elements H2O HCl H2SO4 NH3 Two hydrogen and one oxygen atoms One hydrogen and one chlorine atoms Two hydrogen, one sulfur, and four oxygen atoms One nitrogen and three hydrogen atoms

The basic object of chemistry is elements. What is an element The basic object of chemistry is elements. What is an element? An element is a fundamental substance that can’t be chemically changed or broken down into anything simpler.

How many presently known elements How many presently known elements? 115 elements 90 natural elements 25 artificially elements produced using high energy accelerators

How do chemists represent an element? By using one-, two-, or three-letter symbols of an element Examples: H for hydrogen N for nitrogen Al for aluminum Mg for magnesium Uun for ununnilium

The elements are tabulated in a table called periodic table as shown in Figure 1.1.

Properties can also be classified as either physical or chemical, depending on whether the property involves a change in the chemical makeup of substance Physical properties: Characteristics that do not involve a change in a sample’s chemical makeup

Examples of physical properties: Melting point Boiling point Freezing point Melting point of ice and boiling point of water are physical properties because melting and boiling cause the water to change only in form or phase, but do not in chemical makeup

Chemical properties: Characteristics that do involve a change in a sample’s chemical makeup Example: Rusting of iron Rusting of iron is a chemical property, because iron combines with oxygen and moisture from the air to give the new substance

Some Examples of Physical and Chemical Properties Physical Properties Chemical properties Temperature Color Melting point Electrical conductance Amount Odor Solubility Hardness Rusting (of iron) Combustion (of gasoline) Tarnishing (of silver) Hardening (of cement) Decomposition (of sugar)