Chemistry Grade 7 Sem 1 Final Exam (Chapter 1 Lesson 2 & 3)

Physical Property

A characteristic of a substance that can be observed and measured without changing the identity of the substance.

What can be used to detect physical properties?

Senses

Examples of Physical Properties

color, shape, texture, size, electrical conductivity, density, thermal conductivity, malleability, melting point, boiling point, luster, magnetic attraction, mass, volume

State of Matter

The physical form in which a substance exists

Density

The amount of mass in a given volume

Electrical conductivity

A measure of how well an electric current can move through a substance

Thermal conductivity

The rate at which a substance transfers heat

Malleability

The ability of a substance to be rolled or pounded into various shapes.

Luster

Shininess

Melting point

The temperature at which a substance changes from a solid to liquid

Boiling point

The temperature at which a substance changes from a liquid to gas

Chemical property

A property that describes a substance's ability to change into a new substance with different properties

Examples of chemical properties

Flammability, reactivity with substances such as oxygen, water and acids, rusting, tarnishing

Why are rusting and tarnishing chemical properties?

Because the metal changes.

Flammability

The ability of a substance to burn

What substances are formed when wood burns?

Water, carbon dioxide and ash

Reactivity

The ability of a substance to interact with another substance and form one or more new substances.

Characteristic properties

Properties unique to a substance

Physical change

A change that affects one or more physical properties of a substance

Chemical change

A change that occurs when one or more substances change entirely into new substances with different properties.

What do you do to witness a log's flammability?

You must set it on fire.

Examples of chemical changes

Production of an odor, production of a gas, formation of a precipitate, change in color, change in energyP

How does a chemical change occur when an antacid is dropped into a glass of water?

The tablet makes contact with the water and begins to react to it, so bubbles of gas appear.

Precipitate

When liquids combine to form a solid

Law of Conservation of Mass

In ordinary chemical and physical changes, mass is not created nor destroyed but is only transformed into different substances.