Matter is characterized by its properties. There are two kinds of properties:
Chemical properties describe the abilities of a substance to undergo chemical reactions and to form new substances.
Physical properties are qualities such as color, smell, taste, hardness, density, boiling and melting point, the conduction of electricity, and the ability to dissolve other materials.The physical states of matter, sometimes called phases, are solid, liquid, gas, and plasma. The states of matter can be changed by adding or removing heat energy.
Matter can either be made of only one type of atom or more than one type of atom:
A substance made of only one kind of atom is called an element (for example, gold).
A substance made up of more than one kind of atom is either a compound or a mixture. Compounds will be discussed in Chapter 3. A mixture is a combination of substances that is either homogeneous or heterogeneous.
A homogeneous mixture is also called a solution. A solution is a mix of two or more substances that are not easily observable as distinct from one another (for example, sugar dissolved in water.
A heterogeneous mixture is a mix of two or more substances that are easily observable as distinct from one another another (for example, sand in water or pebbles in cement).
To date, there are 116 known elements. 88 of them are found in abundance on earth.
مقالات قد تفيدك :