States of Matter: Solid, Liquid, and Gas

• All matter exists in one of three states: solid, liquid, or gas.

States of Matter

• Solid has a fixed, definite shape.
• Solid has a fixed, definite volume.
• Particles in a solid have very small distances between them.
• Interactions between particles in a solid are very strong.
• Liquid takes the shape of the container.
• Liquid has a fixed, definite volume.
• Particles in a liquid have small distances between them.
• Interactions between particles in a liquid are strong.
• Gas fills the entire shape of its container.
• The volume of a gas changes to fill its container.
• Particles in a gas have large distances between them.
• Interactions between particles in a gas are very weak.
• Ice is an example of a solid.
• Water is an example of a liquid.
• Steam is an example of a gas.

Changes of State

• The state of matter can be changed by heating or cooling.
• Melting changes a solid to a liquid.
• Boiling changes a liquid to a gas.
• Freezing changes a liquid to a solid.
• Condensation changes a gas to a liquid.
• Sublimation changes a solid to a gas.
• Deposition changes a gas to a solid.

Heating Curve

• A heating curve shows temperature changes of a substance as it is heated.
• AB: Solid is heated until it starts to melt.
• BC: Solid is melting; the temperature remains constant as energy breaks the bonds between particles.
• CD: Liquid is heated until it starts to boil.
• DE: Liquid is boiling; the temperature remains constant as energy breaks the bonds between particles.
• EF: Gas is heated.

Cooling Curve

• A cooling curve shows how the temperature of a substance changes as it is cooled.
• It is the reverse of a heating curve.

Conditional Instructions

Definition

• A conditional instruction is an instruction which permits the execution of a block of instructions only on the condition that the statement is true.

Syntax

• In Python, the syntax of a conditional statement appears as follows:

if condition:
    # Block of instructions to be executed if the statement is true
elif condition2:
    # Block of instructions to be executed if condition2 is true
else:
    # Block of instructions to be executed if all statements are untrue

Example

age = 18
if age >= 18:
    print("You've come of age")
else:
    print("You are underage")

Comparison Operators

Definition

• Comparison Operators are operators that permit the comparison of two values.

List of Comparison Operators

• Here is a list of the operators of comparison in Python:

Example

a = 5
b = 10
if a > b:
    print("a is superior to b")

Logical Operators

Definition

• Logical Operators are operators that permit the combination of statements.

List of Logical Operators

Here is a list of Logical Operators in Python:

Example

age = 20
nationality = "French"
if age >= 18 and nationality == "French":
    print("You are of age and French")

Nested Instructions

Definition

• Nested Instructions are conditional instructions within other conditional instructions.

Example

age = 20
nationality = "French"
if age >= 18:
    if nationality == "French":
        print("You are of age and French")
    else:
        print("You are of age but not French")
else:
    print("You are underage")