There are only 102 known elements as we know of today in the universe. Everything else in the universe is a combination of these elements. For example iron is an element and so is gold. Hydrogen and Oxygen are also basic elements.

Most things in the universe are a combination of other elements. For example water is a combination of 2 parts hydrogen and 1 part oxygen. When iron mixes with oxygen in the air it gets rusted.

An element is identified by its properties. There are two kinds of properties. Chemical properties and Physical Properties.

Chemical properties of an element describes how it mixes or combines with other elements to form new materials.

Here are some physical properties of an element like Iron or Gold.

Color
Odor
Mass
Texture
Hardness

Typically physical properties can be measured with out changing the object.

Rulers
Microscopes
thermometers
scales
Balances

Most elements are metals. In fact 3 out of every 4 elements are metals. Out of the 102 or so elements, about 75 are metals.

Metals are smooth, shiny, bendable, and conduct heat and electricity well.

Metals are shiny, bendable, and conduct heat and electricity. Iron, copper, Silver, and Gold are all metals.

Metals conduct heat and electricity well. Copper is an excellent conductor of electricity. The electrical wiring in a house is made with copper.

We use pans to cook. Because of this pans must be able to trasmit heat well to the food. Pans are also smooth and shiny and hard. These are all properties of metals.

Weight is a measure how heavy something is. How heavy something is depends on two things. One of them is gravity. Something that is heavy on earth might be lighter on the moon as moon has less gravity than earth.

The other one weight depends on is how much mass there is in the object. More mass then more weight.

Because weight is a measure of both mass and gravity one uses a "spring balance" to measure weight. A "spring balance" tells us how much force is applied on the string. This force is proportional to the mass and also the gravity and hence is a measure of its weight.

Weight changes based on gravity. A object is a bit lighter on the top of a tall mountain. An object is much leighter on the surface of a moon. In fact the object has almost no weight in empty space. The object still has mass to it but no weight because there is nothing pulling the object.

Weight is measured using a spring balance. Weight is many times confused with mass. Mass can be measured with a simple balance. If you were to use a balance on ground and on the top of a mountain you will get different results.

That is why a spring balance is needed to measure weight which takes into account not only mass but also gravitational pull.

28 what is mass and how is it different from weight?

30 what tool is used to measure mass?

32 what are the units used to measure mass?

34 what is volume?

36 what is the formula for volume?

38 What is density?

40 what is the formula for density?

42 Compare and contrast object properties and a material's natural properties

44 Give 4 examples of material properties that don't change

46 Calculate the volume for the following objects

48 List the approximate densities of some common materials

Sun and Tilted Earth