Ch 2 - Pt 1: Atoms, Elements, Chemical Bonds/Reactions

What is matter?

Anything that has mass and occupies space.

What are the three states of matter?

Solid, liquid, and gas.

What defines a solid state of matter?

A definite shape and volume.

What defines a liquid state of matter?

A changeable shape but definite volume.

What defines a gas state of matter?

A changeable shape and volume.

What is energy?

The capacity to do work or put matter into motion.

What are the two forms of energy?

Kinetic energy (in action) and potential energy (stored).

What is chemical energy?

Energy stored in the bonds of chemical substances.

What is electrical energy?

Energy resulting from the movement of charged particles.

What is mechanical energy?

Energy directly involved in moving matter.

What is radiant energy?

Energy that travels in waves, such as heat and visible light.

What are elements?

Substances that cannot be broken down into simpler substances by ordinary chemical methods.

Which four elements make up 96% of the human body?

Carbon, oxygen, hydrogen, and nitrogen.

What are trace elements?

Elements required in very minute amounts, often found as part of enzymes.

What are the three subatomic particles of an atom?

Protons, neutrons, and electrons.

What charge do protons carry?

A positive charge (+).

What charge do electrons carry?

A negative charge (-).

What is the mass of neutrons and protons?

Both weigh approximately 1 atomic mass unit (1 amu).

What is the atomic number of an element?

The number of protons in the nucleus of an atom.

What is the mass number of an element?

The total number of protons and neutrons in the nucleus.

What is an isotope?

Atoms of the same element with different numbers of neutrons.

What is the atomic number?

The number of protons in the nucleus of an atom.

What are isotopes?

Structural variations of the same element that have the same number of protons but different numbers of neutrons.

What is atomic weight?

The average of the mass numbers of all isotope forms of an atom.

What is a radioisotope?

An isotope that decomposes to more stable forms and can be used in biological research and medicine.

What are the three main differences between mixtures and compounds?

1. Mixtures do not involve chemical bonding; compounds do. 2. Mixtures can be separated by physical means; compounds require breaking chemical bonds. 3. Mixtures can be heterogeneous or homogeneous; compounds are only homogeneous.

What are the three basic types of mixtures?

Solutions, colloids, and suspensions.

What characterizes a solution?

Solute particles are very tiny, do not settle out, and do not scatter light.

What characterizes a colloid?

Solute particles are larger than in a solution, scatter light, and do not settle out.

What characterizes a suspension?

Solute particles are very large, settle out, and may scatter light.

What is the octet rule?

Atoms tend to have 8 electrons in their valence shell, except for hydrogen and helium.

What is the driving force behind chemical reactions?

Fulfilling the maximum number of electrons in the valence shell.

What are chemically inert elements?

Elements with a complete outermost energy level (valence shell).

What are chemically reactive elements?

Elements with an incomplete outermost energy level (valence shell).

What are the three major types of chemical bonds?

Ionic bonds, covalent bonds, and hydrogen bonds.

How is an ionic bond formed?

By the transfer of electrons from one atom to another, resulting in a cation and an anion.

What type of bond is formed by sharing electrons between atoms?

Covalent bonds.

What type of bond is formed between two atoms sharing three electron pairs?

A triple covalent bond

What is a hydrogen bond?

An attractive force between electropositive hydrogen of one molecule and an electronegative atom of another molecule.

What are the three main types of chemical reactions?

Synthesis, decomposition, and exchange (displacement) reactions.

What occurs in a synthesis reaction?

Atoms or molecules combine to form larger, more complex molecules.

What happens in a decomposition reaction?

A molecule breaks down into smaller molecules or its constituent atoms.

What characterizes an exchange reaction?

Bonds are both made and broken, involving both synthesis and decomposition.

What factors can affect the rate of chemical reactions?

Temperature, concentration of reactants, particle size, and the presence of catalysts.

What is the role of enzymes in chemical reactions?

Enzymes act as biological catalysts that increase the rate of reaction without being changed.

What is the strength of covalent bonds compared to ionic and hydrogen bonds?

Covalent bonds are the strongest, followed by ionic bonds, and then hydrogen bonds.

What does a double covalent bond in a structural formula indicate?

Two pairs of electrons are shared between two atoms.

What is the difference between polar and nonpolar covalent bonds?

Polar covalent bonds have unequal sharing of electrons, while nonpolar covalent bonds have equal sharing.

What happens to the rate of reaction when temperature increases?

The rate of reaction usually increases.

What does increased concentration of reactants do to the rate of reaction?

It usually increases the rate of reaction.

How does particle size affect the rate of chemical reactions?

Smaller particles usually increase the rate of reaction.