Science Test 1

What is Matter?

Matter is what makes up the world around us, consisting of atoms and particles. These fundamental units combine in various ways to form everything from the air we breathe to the water we drink and the solid objects we see.

Types of Matter

There are three primary states of matter:

1. Solid: In solids, atoms are closely packed together in a fixed arrangement, which gives solids a definitive shape and volume. The particles vibrate but do not move from their fixed positions.

2. Liquid: Liquids have a definite volume but take the shape of their container. The particles are close together, but they can move past one another, allowing liquids to flow.

3. Gas: In gases, particles are much farther apart and move freely. Gases do not have a definite shape or volume; they expand to fill their container.

Distinguish Between Physical and Chemical Properties

• Physical Properties: These are characteristics that can be observed or measured without altering the substance's chemical identity. Examples include appearance, shape, size, color, weight, boiling point, melting point, and density.

• Chemical Properties: These properties become evident during a chemical reaction and involve the substance’s ability to react with other substances. Examples include reactivity with oxygen, acidity, flammability, and combustibility.

WHMIS Symbols

WHMIS (Workplace Hazardous Materials Information System) symbols are used in Canada to communicate information about hazardous materials that may be present in the workplace. These symbols provide visual indicators of the type of hazard associated with a substance, such as toxicity, flammability, and explosive potential.

Theory Vs. Law

• Theory: A theory is a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. Theories explain why phenomena occur.

• Law: A law describes a consistent relationship observed in nature, often expressed mathematically, and explains how phenomena happen.

Atomic Theory Contributions

Various scientists have contributed to atomic theory:

• Democritus: Proposed that all matter is made up of tiny, indivisible particles called atoms.

• Dalton: Formulated the atomic theory, which stated that matter is composed of atoms that cannot be created or destroyed, and introduced the concept of atomic mass.

• Thomson: Discovered the electron and proposed the plum pudding model of the atom, which suggested that negatively charged electrons were embedded in a positively charged sphere.

• Rutherford: Conducted the gold foil experiment, leading to the discovery of the atomic nucleus and the realization that atoms are mostly empty space.

• Bohr: Introduced the Bohr model, which depicted electrons orbiting the nucleus at fixed levels of energy.

Definition of Atom

An atom is the smallest unit of matter that retains the properties of an element. It comprises protons (positively charged particles), neutrons (neutral particles), and electrons (negatively charged particles). In an atom, protons and neutrons reside in the nucleus at the center, while electrons orbit around the nucleus at high speeds, approximately 1 billion times per second.

Distinguish Between Protons, Neutrons, and Electrons

• Protons: Positively charged particles located inside the nucleus. The number of protons in an atom determines the element's identity (atomic number).

• Neutrons: Neutrally charged particles also located in the nucleus. Neutrons contribute to the atomic mass but do not affect the charge of the atom.

• Electrons: Negatively charged particles that move rapidly around the nucleus in defined energy levels. The arrangement of electrons determines how an atom interacts chemically.

Relative Mass

Relative mass is a dimensionless quantity that indicates the average mass of atoms of a given element, typically measured relative to carbon-12, which is standardized as 12 atomic mass units (amu).

Terms to Know

• Hazard Symbols: WHMIS symbols indicating potential risks associated with hazardous substances.

• Matter: Anything that has mass and takes up space.

• Mass: Measure of the amount of matter in an object, often expressed in grams or kilograms.

• Volume: The amount of space that a substance occupies, measured in liters or cubic centimeters.

• Properties: Characteristics that define the nature of a substance, including physical and chemical properties.

• Boiling Point: The temperature at which a substance changes from a liquid to a gas.

• Melting Point: The temperature at which a substance transitions from solid to liquid.

• Element: A pure substance consisting of one type of atom, listed in the periodic table.

• Reactivity: The ability of a substance to undergo chemical changes when combined with other substances.

• State: The physical form of matter (solid, liquid, gas).

• Density: The mass per unit volume of a substance, influencing how substances interact.

• Combustibility: A measure of how easily a substance catches fire.

• Luster: A physical property describing how shiny or reflective a surface is.

• Malleability: The ability of a substance to be deformed or molded, often into thin sheets.

• Texture: The feel of a material, described in terms like hard, soft, rough, or smooth.

• Conductivity: The ability of a substance to conduct heat or electricity.

• Model: A representation of an atom or molecule used to visualize and understand its structure and behavior.