Elements and Compounds

 

Photo courtesy: https://www.pace.edu/news/bringing-science-classroom

MODULE IN SCIENCE 7  (Week 2-3)

TOPIC:  MATTER (Elements and Compounds)

Objective: Recognize that substances are classified into elements and compounds (S7MT-Ig-h-5)

Overview

You have probably seen, touched, and tasted hundreds of different things in your life. You have touched wood, steel, ice and many more. In fact, all of the objects around you which have a mass and occupy space are made of matter. Have you ever wondered what these entire things are made of?  What are the properties of elements and compounds? How can we classify  some objects into elements and compounds? What are the different parts of the Periodic Table? What are some common elements and their importance in our body?

Do you know  that there are a lot of things that you can learn about matter? Thus, this module is formulated for you to broaden and deepen your knowledge about substances. You will find out that substances, are of various kinds. Being so, substances may also be further classified into smaller groups, such as elements and compounds.

A series of activities will gear you in answering the questions above. In this manner, you will see the better connection between compounds and elements, that is, compounds are made up of elements. The periodic table will also be introduced to familiarize you with the elements  and their characteristic that distinguishes them.

Keep this in Mind!

Matter is defined as anything that takes up space and has mass. Matter exists in many diverse forms, each with its own characteristics. Rocks, metals, and glasses are just few examples of what seems an endless assortment of matter.

Matter is categorized into mixture and substance. Substance is broken down to compounds and elements.

Element is a substance that cannot be broken down by other substances by chemical reactions. There are 118 elements. Each element has different set of properties. No two elements have the same set of properties. Just like the two elements hydrogen and oxygen. Even though they are both in gaseous state at room temperature, they behave differently when exposed to a flame or spark of flame. Hydrogen gives off a “pop” sound when ignited; while oxygen induces a brighter spark. This difference in behavior implies a difference in property. In effect, hydrogen and oxygen are different substances, or to be more specific, they are different elements.

Scientists agreed to give symbols for each element. This is very helpful especially to those elements with long names. Instead of writing the full names, a one-letter or two-letter symbol may be used. You can find these symbols in the periodic table too. It is written inside the same box for that element. For instance, O is the symbol for oxygen.

For the two-letter symbols, most of them start with the first letter of the element. Notice that the second letter in the symbol may be any letter found in the element’s name. Notice as well that only the first letter is capitalized for the two-letter symbols.

There are symbols that use letters that were taken from the ancient name of the element. Examples of ancient names are ferrum (iron), argentum (silver), hydrargyrum (mercury) and plumbum (lead).

Chemistry is the study of physical matter, which is classified in many different ways, such as state of matter (gas, liquid or solid), chemical form (element, mixture or compound), chemical structure (atoms or molecules, etc.) and so on.

 It is important to understand the words element, mixture and compound, because these convey useful information. Substance, which can be used to refer to either an element or a compound - but not to a mixture because a 'substance' always has a definite composition. The most general word is matter which can be used to refer to any of substances, elements, mixtures or compounds.

Element - consist of only one type of atom , which may, or may not join together to form molecules or large structures, therefore: can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen) and cannot be broken down into a simpler type of matter by either physical or chemical techniques.

Compound - whose molecules consist of one atom of one element chemically joined with two atoms of another element.

 Let's check your understanding!

Activity 1:  “What Am I?” 

  Direction: Check the appropriate column below if it is an element or a compound. Number 1 is done for you. 

Activity  2: “Elements or Compounds?”

        Direction: Write E if it is an Element and C if it a Compound.

Remember, each shape symbolizes an element.