Introduction to Chemistry I (MAE1106)
Chapter 1: Properties, Measurement and Units
All things we can see, or touch, whether books, pencils, telephones, or people as they have some thing in common. They are all composed of matter which is defined as anything that takes up space and has mass.
Matter is generally considered to be a substance (often a particle) that has rest mass and (usually) also volume. Mass and weight are not really the same. The mass of a body is a measure of its resistance to a change in its velocity. Weight refers to the force with which an object of a certain mass is attracted by gravity to the earth or other body that may be near such as moon.
o Liquid is distinguished by its malleable shape (is able to form into the shape of its container), but constant volume. In a liquid, atoms are close together but not in a fixed arrangement.
o Gas is made up of atoms that are separate. However, unlike solid & liquid, a gas has no fixed shape and volume.
Example: When liquid water (H2O) freezes into a solid state (ice) -- It appears different/changed; However, the composition is still: 11.19% hydrogen and 88.81% oxygen by mass.
Chemical (Properties and Changes)
Chemical Property: Any characteristic that gives a sample of matter the ability/inability to undergo a change that alters its composition.
Examples: Alkali metals react with water; Paper's ability to burn.
Chemical Change: Change in which one or more kinds of matter are transformed to new kinds of matter with altered compositions.
(Or Chemical Reaction):
• Magnesium + Oxygen → Magnesium Oxide or 2 Mg + O2 → 2 MgO
• Iron + Oxygen → Iron Oxide/ Rust or 2 Fe + 3 O2 → Fe2O3
Classification of Matter
The matter can be classified in two different ways; (1) according to its state, and (2) according to its composition
1. The States of Matter: Solid, Liquid, and Gas
Matter can exist in three different states, solid, liquid, and gas, based on the way the atoms and molecules are arranged inside them. These three states are known as three different states of matter. In solids, atoms or molecules are tightly bound to one another thereby creating a rigid nature. Each atom or molecule is caged by its neighbors creating non-mobility, although they might vibrate around the equilibrium position. Here attractive forces are very strong. Consequently, solids have definite shapes and volumes. Some examples of solids are diamond, metals, and ice.
In liquids, the atoms or molecules are not as tightly bound as in solids and due to that they have some freedom to move around. They still experience attractive forces but not as strong as solids. In addition, they also begin to experience some repulsive forces. Thus, liquids have definite volume but not definite shape- they assume the shape of the container. Due to their flexibility, the liquids can be poured from one container to another. Some common examples are water, gasoline, and alcohol at room temperature.
In gases, the atoms or molecules are far apart due to they are not bounded at all, meaning, they do not have any attractive forces but only repulsive forces. Due to that they can occupy a large volume. They do not have their own shape or volume, but assume the shape and the volume of the container. Some common examples are oxygen, hydrogen, and helium at room temperature.
2. Classification of Matter based on Composition
When we talk about matter, usually we talk about a substance, which possesses distinct properties and has a...