CHM 101 Flashcards
What is an atom?
The smallest unit of matter that retains the properties of an element.
What are molecules?
Groups of two or more atoms bonded together.
What is an element?
A pure substance that cannot be broken down into simpler substances by chemical means.
What is a compound?
A substance formed when two or more elements are chemically bonded together.
True or False: All compounds are molecules.
True
What is the chemical formula for water?
H2O
Fill in the blank: The nucleus of an atom contains _____ and _____.
protons; neutrons
What particle has a negative charge?
Electron
True or False: Electrons are located in the nucleus of an atom.
False
What is the periodic table?
A tabular arrangement of all known chemical elements organized by atomic number and properties.
What is the atomic number of an element?
The number of protons in the nucleus of an atom.
Fill in the blank: An ionic bond is formed when electrons are _____ from one atom to another.
transferred
What is a covalent bond?
A bond formed when two atoms share one or more pairs of electrons.
What is a chemical reaction?
A process that involves the rearrangement of the molecular or ionic structure of a substance.
True or False: In a chemical reaction, the total mass of the reactants equals the total mass of the products.
True
What are reactants?
The starting substances in a chemical reaction.
What are products?
The substances formed as a result of a chemical reaction.
What is a catalyst?
A substance that increases the rate of a chemical reaction without being consumed.
Fill in the blank: The law of conservation of mass states that mass is _____ in a chemical reaction.
neither created nor destroyed
What is a mixture?
A combination of two or more substances that are not chemically bonded.
What is an example of a heterogeneous mixture?
Salad
What is an example of a homogeneous mixture?
Saltwater
True or False: All mixtures can be separated by physical means.
True
What is a solution?
A homogeneous mixture where one substance is dissolved in another.
What is the role of a solvent in a solution?
The substance that dissolves the solute.
What is the role of a solute in a solution?
The substance that is dissolved in the solvent.
What is the difference between an element and a compound?
An element is a pure substance that cannot be broken down, while a compound is made of two or more elements chemically bonded.
Fill in the blank: The smallest unit of a compound is called a _____ .
molecule
What is a chemical equation?
A symbolic representation of a chemical reaction.
What are coefficients in a chemical equation?
Numbers placed before compounds to indicate the number of molecules involved in the reaction.
What are subscripts in a chemical formula?
Numbers that indicate the number of atoms of each element in a molecule.
Fill in the blank: The process of a solid turning into a gas is called _____ .
sublimation
What is the process of a gas turning into a liquid called?
Condensation
What is the process of a liquid turning into a solid called?
Freezing
What is the process of a solid turning into a liquid called?
Melting
True or False: Chemical bonds can be broken and formed during chemical reactions.
True
What is activation energy?
The minimum energy required for a chemical reaction to occur.
What is an endothermic reaction?
A reaction that absorbs energy from its surroundings.
What is an exothermic reaction?
A reaction that releases energy to its surroundings.
Fill in the blank: The pH scale measures the _____ of a solution.
acidity or alkalinity
What is a neutral solution on the pH scale?
A solution with a pH of 7.
What is an acid?
A substance that donates protons (H+) in a solution.
What is a base?
A substance that accepts protons (H+) in a solution.
True or False: Acids have a pH less than 7.
True
True or False: Bases have a pH greater than 7.
True
What is a chemical symbol?
A one or two-letter representation of an element.
What is the chemical symbol for gold?
Au
What is the chemical symbol for sodium?
Na
What is the chemical symbol for carbon?
C
Fill in the blank: The number of neutrons can be found by subtracting the atomic number from the _____ .
mass number
What is an isotope?
Atoms of the same element that have different numbers of neutrons.
True or False: Isotopes have the same chemical properties.
True
Fill in the blank: The main component of the nucleus is _____ .
protons and neutrons
What is a valence electron?
An electron in the outermost shell of an atom that is involved in chemical bonding.
How many valence electrons does carbon have?
4
What is a chemical reaction’s rate?
The speed at which reactants are converted into products.
What factors can affect the rate of a chemical reaction?
Temperature, concentration, surface area, and presence of catalysts.
Fill in the blank: A _____ reaction occurs when two or more substances combine to form a single product.
synthesis
What is a decomposition reaction?
A reaction where a single compound breaks down into two or more simpler products.
What is a single replacement reaction?
A reaction where one element replaces another in a compound.
What is a double replacement reaction?
A reaction where the anions and cations of two different compounds exchange places.
Fill in the blank: The process of forming a solid from a solution during a chemical reaction is called _____ .
precipitation
What is the significance of the mole in chemistry?
The mole is a unit that measures the amount of substance, allowing chemists to count particles by weighing.
What is molarity?
A measure of the concentration of a solute in a solution, expressed as moles of solute per liter of solution.
What does Avogadro’s number represent?
The number of particles in one mole of a substance, approximately 6.022 x 10^23.
True or False: A chemical change is reversible.
False
What is a physical change?
A change that affects one or more physical properties of a substance without altering its chemical composition.
What is combustion?
A chemical reaction that occurs when a substance reacts with oxygen to produce energy in the form of heat and light.
Fill in the blank: The pH of a strong acid is typically _____ .
less than 3
What is a buffer?
A solution that resists changes in pH when small amounts of acid or base are added.
