Chemistry unit 1 study guide

What is chemistry

Chemistry is the study of the composition, structure, properties, and changes of matter.

Why is chemistry called the “Central Science”

It bridges and connects physical sciences with life sciences and applied disciplines like biology, medicine, geology, and environmental science.

What is the macroscopic domain of chemistry

The realm of everyday things large enough to be sensed directly by human sight or touch (e.g., density, solubility, physical state).

What is the microscopic domain of chemistry

The realm of things visited in the imagination or observed through advanced instruments like microscopes (e.g., atoms, molecules, ions, chemical bonds).

What is the symbolic domain of chemistry

The specialized language used to represent components of the macroscopic and microscopic domains (e.g., chemical symbols, formulas, equations, graphs).

Section 1.2: Phases and Classification of Matter

What are the physical properties of a solid

Fixed shape and definite volume; particles are close together.

What are the physical properties of a liquid

Takes the shape of its container with a flat/horizontal surface; fixed volume; particles are spaced slightly apart.

What are the physical properties of a gas

Takes both the shape and volume of its container (expands to fill); particles are spaced well apart.

What is the Law of Conservation of Mass (or Matter)

In a chemical or physical change, matter (mass) cannot be created or destroyed. The total mass before a change equals the total mass after the change.

What is mass

An object’s measure of the amount of matter in it; remains constant regardless of location.

What is weight

The force that gravity exerts on an object; changes depending on the gravitational force acting on it.

What is a pure substance

A substance that has a constant composition throughout.

What is an element

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

What is a compound

A pure substance composed of two or more elements chemically combined that can be broken down by chemical changes.

What is a homogeneous mixture (solution)

A mixture with a uniform composition throughout.

What is a heterogeneous mixture

A mixture with a composition that varies from point to point.

What is an atom

The smallest particle of an element that has the properties of that element.

What is a molecule

Two or more atoms connected by chemical bonds.

Section 1.3: Physical and Chemical Properties & Changes

What is a physical property

A characteristic of matter not associated with a change in its chemical composition (e.g., density, color, melting point).

What is a chemical property

The ability or inability of matter to change into another type of matter (e.g., flammability, toxicity, acidity).

What is a physical change

A change in the state or properties of matter without any change in its chemical composition (e.g., melting ice, dissolving sugar).

What is a chemical change

A change that produces one or more types of matter that differ from the matter present before the change (e.g., rusting, burning).

What are the 4 common indicators of a chemical reaction

Color change occurs; gas is produced; energy is produced or absorbed (heat/light); a precipitate forms.

What is an extensive property

A property that depends on the amount of matter present (e.g., mass, volume).

What is an intensive property

A property that does not depend on the amount of matter present (e.g., temperature, density).

Chapter 1 Study Guide Questions

Question 1 — How is a hypothesis tested

A hypothesis can be tested by experiment; water will freeze if the temperature is below 0°C (32°F).

Question 2a — Is “Falling barometric pressure precedes the onset of bad weather” a Law, Theory, or Hypothesis

Law, because it describes the same relationship between falling pressure and bad weather.

Question 2b — Is “All life on earth has evolved from a common ancestor through natural selection” a Law, Theory, or Hypothesis

Theory, because it explains how life has changed over time through natural selection.

Question 2c — Is “My truck’s gas mileage has dropped significantly, probably because it’s due for a tune-up” a Law, Theory, or Hypothesis

Hypothesis, because it predicts what will happen and can be tested.

Question 3a — Is “The pressure of a sample of gas is directly proportional to the temperature of the gas” a Law, Theory, or Hypothesis

Law, because it describes a general pattern in nature.

Question 3b — Is “Matter is composed of tiny particles that can combine in specific ratios…” a Law, Theory, or Hypothesis

Theory, because it is a widely accepted explanation of the behavior of matter supported by experimental evidence.

Question 3c — Is “At a higher temperature, solids (such as salt or sugar) will dissolve better in water” a Law, Theory, or Hypothesis

Hypothesis, because it is an unsure explanation that can be tested by experimentation.

Question 4a — Is “The mass of a lead pipe is 14 lb” Macroscopic, Microscopic, or Symbolic

Macroscopic, because it is talking about the mass of a lead pipe that can be directly measured.

Question 4b — Is “The mass of a certain chlorine atom is 35 amu” Macroscopic, Microscopic, or Symbolic

Microscopic, because it is talking about atoms and the mass of one chlorine atom.

Question 4c — Is “A bottle with a label that reads Al contains aluminum metal” Macroscopic, Microscopic, or Symbolic

Symbolic, because it uses the Al symbol, but also macroscopic because it refers to aluminum metal.

Question 4d — Is “Al is the symbol for an aluminum atom” Macroscopic, Microscopic, or Symbolic

Symbolic, because it uses the Al symbol, and microscopic because it refers to an aluminum atom.

Question 5a — Is “A sulfur molecule contains eight sulfur atoms” Macroscopic, Microscopic, or Symbolic

Microscopic, because it describes atoms.

Question 5b — Is “Copper wire has a density of about 8 g/cm³” Macroscopic, Microscopic, or Symbolic

Macroscopic, because the density of copper wire can be measured directly.

Question 5c — Is “The bottle contains 15 grams of Ni powder” Macroscopic, Microscopic, or Symbolic

Macroscopic, because the mass of the nickel powder can be measured.

Question 5d — Is “A sulfur molecule is composed of eight sulfur atoms” Macroscopic, Microscopic, or Symbolic

Microscopic, because it refers to atoms inside a sulfur molecule.

Question 6 — How does explaining gas pressure using molecular movement demonstrate the microscopic domain

It explains pressure by describing how individual gas molecules move and hit container walls, which cannot be seen directly.

Question 7 — Is measuring double the heat to melt 2 lbs of ice vs. 1 lb of ice macroscopic or microscopic

Macroscopic, because it measures an observable amount of heat needed to melt physical ice.

Question 8 — How do mass and weight differ when an object changes locations

Mass measures the amount of matter and never changes with location; weight depends on gravity, so it changes with location.

Question 9a — What are the volume and shape properties of a solid

Definite shape and definite volume.

Question 9b — What are the volume and shape properties of a liquid

Definite volume, but takes the shape of its container.

Question 9c — What are the volume and shape properties of a gas

No definite shape and no definite volume.

Question 10 — How do heterogeneous and homogeneous mixtures differ

Heterogeneous mixtures are not uniform throughout, while homogeneous mixtures are uniform throughout.

Question 11 — How do homogeneous mixtures and pure substances differ

A homogeneous mixture contains two or more substances, while a pure substance contains only one type of substance.

Question 12 — How do elements and compounds differ

An element contains only one type of atom, while a compound contains two or more different elements chemically combined.

Question 13 — How do molecules of elements differ from molecules of compounds

Molecules of an element contain only one type of atom, while molecules of a compound contain atoms of two or more different elements.

Question 14 — How does an atom differ from a molecule

An atom is a single particle of an element, while a molecule consists of two or more atoms chemically bonded together.

Question 15 — What pure compounds are found in common household items

Toothpaste (sodium fluoride), table salt (sodium chloride), and sugar (sucrose).

Question 16a — How would you classify air as an Element, Compound, or Mixture

Mixture.

Question 16b — How would you classify water as an Element, Compound, or Mixture

Compound.

Question 16c — How would you classify nitrogen as an Element, Compound, or Mixture

Element.

Question 16d — How would you classify gasoline as an Element, Compound, or Mixture

Mixture.

Question 16e — How would you classify sucrose as an Element, Compound, or Mixture

Compound.

Question 16f — How would you classify iodine crystals as an Element, Compound, or Mixture

Element.

Question 16g — How would you classify gelatin as an Element, Compound, or Mixture

Mixture.

Question 17a — How would you classify iron as an Element, Compound, or Mixture

Element.

Question 17b — How would you classify oxygen as an Element, Compound, or Mixture

Element.

Question 17c — How would you classify mercury oxide as an Element, Compound, or Mixture

Compound.

Question 17d — How would you classify pancake syrup as an Element, Compound, or Mixture

Mixture.

Question 17e — How would you classify carbon dioxide as an Element, Compound, or Mixture

Compound.

Question 17f — How would you classify a substance composed of 1 hydrogen atom and 1 chlorine atom as an Element, Compound, or Mixture

Compound.

Question 17g — How would you classify baking powder as an Element, Compound, or Mixture

Mixture.

Question 18 — What is the difference between a sulfur atom and a sulfur molecule

A sulfur atom is a single atom, whereas a sulfur molecule contains multiple sulfur atoms bonded together.

Question 19 — How do molecules of oxygen (O₂), hydrogen (H₂), and water (H₂O) differ

Oxygen molecules contain two oxygen atoms, hydrogen molecules contain two hydrogen atoms, and water molecules contain two hydrogen atoms combined with one oxygen atom.

Question 20 — Why do astronauts in space have mass even if they appear weightless

They have mass because they still consist of matter; they appear weightless because they are in free fall without gravity pushing them against a surface.

Question 21a — What chemicals are consumed during the operation of an automobile

Gasoline and oxygen.

Question 21b — What chemicals are produced during the operation of an automobile

Carbon dioxide, water vapor, and exhaust gases.

Question 22a — How would you classify a book by state/composition

Solid.

Question 22b — How would you classify water by state/composition

Liquid / Compound.

Question 22c — How would you classify oxygen by state/composition

Gas / Element.

Question 22d — How would you classify copper by state/composition

Element.

Question 22e — How would you classify salt water by state/composition

Homogeneous mixture.

Question 22f — How would you classify cereal with milk by state/composition

Heterogeneous mixture.

Question 22g — How would you classify gold by state/composition

Pure substance / Element.

Question 22h — How would you classify air by state/composition

Homogeneous mixture.

Question 22i — How would you classify orange juice by state/composition

Mixture.

Question 23 — A 23.2 g iron nail rusts to a mass of 24.1 g. How much oxygen combined with the iron

24.1 g − 23.2 g = 0.9 g of oxygen.

Question 24a — Will 1 lb of fresh bread dough weigh more, less, or the same after baking

Less than 1 lb, because water vapor and gases escape during baking.

Question 24b — Will burned magnesium weigh more, less, or the same as the original magnesium ribbon

Greater, because oxygen from the air combines with the magnesium.

Question 24c — Will heating mercury oxide in a sealed flask change its total mass

The mass remains the same, because the flask is sealed so no matter can enter or escape.

Question 25a — If 200.0 g of sugar ferments in a closed container, what is the total mass of products

200.0 g, because mass is conserved in a closed container.

Question 25b — If fermentation takes place in an open container, how does final mass compare

It will be less than 200.0 g, because carbon dioxide gas escapes.

Question 25c — If 200.0 g of sugar produces 97.7 g of CO₂, what mass of ethanol is produced

200.0 g − 97.7 g = 102.3 g of ethanol.

Question 26a — Is “Fluorine is a pale yellow gas” a Physical or Chemical Property

Physical property.

Question 26b — Is “Fluorine reacts with most substances” a Physical or Chemical Property

Chemical property.

Question 26c — Is “Fluorine freezes at −220°C” a Physical or Chemical Property

Physical property.

Question 26d — Is “Fluorine melts at −220°C” a Physical or Chemical Property

Physical property.