Chemistry 2nd Quarter

What is chemistry?

The scientific study of matter, its properties, how it interacts with energy, and how it changes.

Why is chemistry called the 'central science'?

Because it connects other natural sciences like physics, biology, and geology.

What is matter?

Anything that has mass and takes up space.

What distinguishes a pure substance from a mixture?

A pure substance has a uniform and definite composition, while a mixture is a physical combination of two or more substances.

What is an element?

A pure substance that cannot be broken down into simpler substances by chemical means.

Give an example of a compound. What defines it?

Water (H2O); a compound is formed when two or more different elements are chemically bonded together in fixed proportions.

What are homogeneous mixtures?

Uniform compositions throughout, such as saltwater or air.

What is an atom?

The smallest unit of an element that retains the chemical identity of that element.

Describe protons and their role in an atom.

Protons are positively charged particles located in the nucleus; they determine the atomic number and identity of the element.

What is the atomic number (Z)?

The number of protons in an atom's nucleus.

What is the mass number (A)?

The total number of protons and neutrons in an atom's nucleus.

What are isotopes?

Atoms of the same element that have different numbers of neutrons.

What characterizes a solid?

A solid has a definite shape and volume, with particles that are tightly packed and vibrate in fixed positions.

What happens in a chemical reaction?

There is a rearrangement of the atomic structure of substances, leading to the formation of new substances.

What are reactants in a chemical reaction?

The starting substances involved in a chemical reaction.

What does the Law of Conservation of Mass state?

Mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Define an ionic bond.

An ionic bond is formed between a metal and a non-metal, involving the transfer of electrons that create ions which attract each other.

What is a covalent bond?

A covalent bond is formed between two non-metals, involving the sharing of electrons.

What is stoichiometry?

The quantitative study of reactants and products in chemical reactions.

Define acids according to the Arrhenius definition.

Acids are substances that produce hydrogen ions (H+) in solution.

What is the pH scale used for?

The pH scale measures the acidity or basicity of a solution, with values ranging from 0 to 14.