Chemistry Flashcards

Questions and Answers

What is chemistry?

The study of matter, its properties, the changes that matter undergoes, and the energy associated with these changes.

What is matter?

Anything that has both mass and volume.

What is meant by composition?

The types and amounts of simpler substances that make up a sample of matter.

What are properties?

The characteristics that give each substance a unique identity. Signup and view all the answers

What are substances?

A type of matter that has a defined, fixed composition. Signup and view all the answers

What are the three types of matter?

Elements, molecules, and compounds. Signup and view all the answers

What are elements?

The simplest type of matter with unique physical and chemical properties. Signup and view all the answers

What are molecules?

A structure that consists of two or more atoms that are chemically bound together. Signup and view all the answers

What are compounds?

Substances that consist of two or more different elements that are chemically bound. Signup and view all the answers

What are the two defining features of compounds?

A compound's properties are different from the properties of its elements. Signup and view all the answers

What are mixtures?

Consists of two or more substances that are physically intermingled and not chemically combined. Signup and view all the answers

What are the three features of mixtures?

<ol> <li>Not a substance. 2) Components retain their individual properties. 3) Can be separated into components by physical change.</li> </ol> Signup and view all the answers

What are the three mass laws?

<ol> <li>The law of mass conservation. 2) The law of definite (or constant) composition. 3) The law of multiple proportions.</li> </ol> Signup and view all the answers

What is the Law of Mass Conservation?

The total mass of substances does not change during a chemical reaction. Signup and view all the answers

What is the Law of Definite (or Constant) Composition?

A particular compound is composed of the same elements in the same parts (fractions) by mass, regardless of its source. Signup and view all the answers

What is the Law of Multiple Proportions?

If elements A & B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers. Signup and view all the answers

What are Dalton's Atomic Theory's four postulates?

<ol> <li>All matter consists of atoms. 2) Atoms of an element cannot be converted into atoms of another element. 3) Atoms of an element are identical in mass. 4) Compounds result from the chemical combination of a specific ratio of atoms of different elements.</li> </ol> Signup and view all the answers

Which of Dalton's postulates explains the law of mass conservation?

Postulate 1, 2, and 3. Signup and view all the answers

Which of Dalton's postulates explains the law of definite (or constant) composition?

Postulate 3 and 4. Signup and view all the answers

Which of Dalton's postulates explains the law of multiple proportions?

Postulate 1 and 3. Signup and view all the answers

What did J.J. Thomson find and propose?

Electrons using a cathode ray and proposed that electrons were lighter than the atom itself. Signup and view all the answers

What model is J.J. Thomson famous for?

The plum-pudding model. Signup and view all the answers

What is Ernest Rutherford known for?

The nuclear model of atoms and identifying protons. Signup and view all the answers

Study Notes

Chemistry Overview

Chemistry is the study of matter, its properties, changes, and the energy involved in these processes.
Matter is anything with mass and volume, essentially the "stuff" of the universe.

Composition and Properties

Composition refers to the types and amounts of simpler substances in a sample of matter.
Properties are characteristics that provide each substance with a unique identity.
Substances have a defined, fixed composition.

Types of Matter

Three categories of matter exist: Elements, Molecules, and Compounds.
Elements are the simplest type of matter, consisting of only one type of atom and cannot be broken down further.
Molecules consist of two or more atoms chemically bonded and function as independent units.
Compounds are composed of two or more different elements that are chemically bound.

Features of Compounds and Mixtures

Compounds have fixed parts by mass and different properties than their constituent elements; they can be broken down into simpler substances.
Mixtures contain two or more substances intermingled physically, without chemical combination.
Mixtures retain their individual properties and can be separated by physical changes.

Mass Laws in Chemistry

Three fundamental mass laws: Law of Mass Conservation, Law of Definite Composition, Law of Multiple Proportions.
Law of Mass Conservation states that total mass remains constant during a chemical reaction; mass of reactants equals mass of products.
Law of Definite Composition asserts that a compound always contains the same elements in the same mass ratios, regardless of source.
Law of Multiple Proportions indicates that when two elements form different compounds, the masses of one element that combine with a fixed mass of the other can be expressed in small whole number ratios.

Dalton's Atomic Theory

Dalton's Atomic Theory includes four postulates about the nature of matter and atoms.
Matter is composed of indivisible atoms that cannot be created or destroyed.
Atoms of an element are identical in properties and distinct from atoms of other elements.
Compounds result from the combination of atoms in specific ratios.

Connection of Laws to Atomic Theory

Dalton's first three postulates are linked to the law of mass conservation, affirming the unchanged nature of atoms during reactions.
The law of definite composition is explained by postulates three and four, relating to fixed mass relationships in compounds.
The law of multiple proportions is explained by postulates one and three, indicating the occurrence of small whole number ratios in atom combinations.

Discoveries in Atomic Structure

J.J. Thomson discovered electrons via cathode ray experiments, proposing they are lighter than atoms and developed the plum-pudding model to represent negatively charged particles.
Ernest Rutherford is noted for presenting the nuclear model of atoms, recognizing protons and showing that atoms have a dense, positive nucleus surrounded by electrons.

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Test your knowledge with these chemistry flashcards. Each card covers fundamental concepts such as matter, composition, and the basic definition of chemistry. Perfect for students looking to reinforce their understanding of essential chemistry terms.