Science Chapter 2 Flashcards

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Questions and Answers

What is matter?

Anything that has mass and takes up space.

What is an atom?

Smallest particle of an element that still retains the properties of the element.

What is a substance?

An element or compound that cannot be broken down into simpler components and maintains the properties of the original substance.

What is an element?

A pure substance that is made of only one type of atom. Signup and view all the answers

What is a molecule?

A group of atoms connected by a covalent bond. Signup and view all the answers

What is a compound?

Atoms of more than one type of element that are chemically bonded together. Signup and view all the answers

What is a mixture?

A combination of two or more individual substances which do not change or combine chemically but instead retain their own individual properties. Signup and view all the answers

What is a heterogeneous mixture?

A mixture in which the components are not mixed evenly and each component retains its own properties. Signup and view all the answers

What is a homogeneous mixture?

A solid, liquid or gas that contains two or more substances blended evenly throughout. Signup and view all the answers

What is a physical change?

A change in size, shape or state of matter in which the identity of the substance remains the same. Signup and view all the answers

What is a chemical change?

Change of one substance into a new substance. Signup and view all the answers

What does the law of conservation of mass state?

The mass of all substances present before a chemical change equals the mass of all the substances remaining after the change. Signup and view all the answers

Explain the relationship between atoms, elements, and compounds.

Atoms are microscopic particles that make up everything. An element is made of one type of atom, and compounds are formed from two or more elements. Signup and view all the answers

How do elements and compounds differ?

Elements are composed of the same atomic atoms/molecules, while compounds are composed of two or more different elements. Signup and view all the answers

How do molecules and compounds differ?

Molecules can consist of the same or different types of atoms, whereas compounds must be made up of different elements. Signup and view all the answers

What is a chemical formula?

Tells what elements a compound contains and the exact number of the atoms of each element in a unit of that compound. Signup and view all the answers

What elements make up the earth's surface, oceans, atmosphere, and living matter?

Carbon, hydrogen, and oxygen. Signup and view all the answers

What is the difference between a compound and a mixture?

A compound contains two or more elements chemically combined in a fixed proportion, while a mixture is a physical blend of two or more substances that are not chemically combined. Signup and view all the answers

Give evidence that indicates a chemical change is happening.

Signs include gas production, temperature change, disappearance of a substance, formation of a solid, color change, new odor, and production of light, heat, or sound. Signup and view all the answers

Study Notes

Key Concepts in Matter and Chemistry

Matter: Defined as anything with mass and volume, encompassing all physical objects.
Atom: The fundamental unit of an element retaining its properties; the smallest particle of an element.

Types of Substances

Substance: Refers to an element or compound that cannot be reduced further without losing its properties. Examples include gold, tin, and aluminum.
Element: A pure substance made of only one type of atom such as hydrogen and oxygen.
Molecule: Formed when two or more atoms are connected by covalent bonds; examples include diatomic gases like H₂ and O₂.
Compound: A substance formed when atoms of different elements chemically bond. Examples: water (H₂O), carbon dioxide (CO₂), and methane (CH₄).

Mixtures

Mixture: A blend of two or more substances that retain their original properties without chemical change; can consist of solids, liquids, or gases.
Heterogeneous Mixture: Components are not uniformly distributed and retain individual properties, e.g., oil and vinegar, trail mix.
Homogeneous Mixture: Substances are evenly distributed, creating a single-phase solution; examples include sweetened tea and salt water.

Changes in Matter

Physical Change: Alteration affecting size, shape, or state without changing chemical identity; examples are melting ice or crumpling paper.
Chemical Change: Transformation resulting in the formation of new substances; observable in reactions such as burning wood or dissolving salt.

Principles of Mass

Law of Conservation of Mass: Asserts mass remains constant in chemical reactions; mass before a change equals mass after.

Relationships Among Atoms, Elements, and Compounds

Atoms compose all matter; an element consists of identical atoms, while a compound consists of atoms from two or more different elements.
Example: Hydrogen is an element; water (H₂O) is a compound formed from hydrogen and oxygen.

Differentiation of Molecules and Compounds

Molecules: Can consist of the same type of atoms (e.g., O₂), whereas Compounds comprise two or more different elements (e.g., H₂O).
All compounds are molecules, but not all molecules qualify as compounds.

Chemical Formulas and Earth's Composition

Chemical Formula: Indicates the types and numbers of atoms in a substance.
Earth's composition predominantly consists of carbon, hydrogen, and oxygen.

Mixtures vs. Compounds

Mixtures: Involve physical combinations of substances that retain individual characteristics (e.g., trail mix).
Compounds: Form through chemical bonds, resulting in a substance with fixed proportions (e.g., cake batter).

Indicators of Chemical Change

Signs of a chemical change may include production of gas, temperature alteration, substance disappearance, solid formation, color change, odor change, or energy release such as heat or light.

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Description

Test your knowledge with these flashcards from Chapter 2 of your science curriculum. The cards cover essential concepts such as matter, atoms, and substances, helping you grasp fundamental scientific principles. Perfect for quick revision or study sessions!