Chem Final

Question 1

Define chemistry

Answer 1

A science that deals with the composition, structure, and properties of substances and with the changes

Question 2

Define matter

Answer 2

Anything that takes up space and can be weighed

Question 3

Identify the 3 states of matter and describe the general characteristics of each

Answer 3

Solid, liquid, and gas. Solids have a definite shape and volume. Liquids have a definite volume, but take the shape of the container. Gases have no definite shape or volume

Question 4

Tell the difference between an element and a compound

Answer 4

Elements are pure substances which are composed of only one type of atom. Compound are substances which are formed by two or more different types of elements that are united chemically in fixed proportions. There are nearly 118 elements (at present) of which nearly 94 occur naturally on Earth

Question 5

Identify if a physical or chemical change has occurred

Answer 5

In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed

Question 6

Write numbers in scientific notation

Answer 6

A number is written in scientific notation when a number between 1 and 10 is multiplied by a power of 10. For example, 650,000,000 can be written in scientific notation as 6.5 ✕ 10^8

Question 7

Give examples of units for length, mass, temperature, and time

Answer 7

The SI units for length, mass, time, and temperature are metre, kilogram, second, and Kelvin respectively. These units are defined based on fundamental constants and ensure consistency and accuracy in scientific measurements

Question 8

Describe how to do dimensional analysis unit conversion

Answer 8

Performing dimensional analysis begins with finding the appropriate conversion factors. Then, you simply multiply the values together such that the units cancel by having equal units in the numerator and the denominator

Question 9

Read and write chemical formula

Answer 9

For example, the molecular formula for acetic acid, the component that gives vinegar its sharp taste, is C2H4O2. This formula indicates that a molecule of acetic acid (Figure 3.3. 6) contains two carbon atoms, four hydrogen atoms, and two oxygen atoms. The ratio of atoms is 2:4:2

Question 10

List the 3 subatomic particles and their properties (charge and relative mass)

Answer 10

Electrons are negatively charged particles and its mass is 1/1840 the mass of a hydrogen atom. Protons are positively charged particles. Each proton has a mass about 1840 times that of an electron. Neutrons are subatomic particles with no charge but with a mass nearly equal to that of a proton.

Question 11

Discuss where each of the 3 subatomic particles are located in an atom

Answer 11

Atoms are made up of protons and neutrons located within the nucleus, with electrons in orbitals surrounding the nucleus

Question 12

Discuss the difference between the atomic number and mass number

Answer 12

The major difference between atomic number and mass number is that the atomic number states the number of protons present in an atom whereas, the mass number indicates the total number of protons and the number of neutrons present in an atom

Question 13

Define an isotope and interpret an isotope symbol

Answer 13

Isotopes are atoms of the same element that have the same number of protons (i.e., atomic number, “Z”) but a different number of neutrons, meaning that their mass number, “A”, varies. Take hydrogen, for example. It has three naturally occurring isotopes–1H, 2H, and 3H

Question 14

Identify the groups/families of the periodic table

Answer 14

Families of the Periodic Table. On the periodic table, there are families which are groups of elements with similar properties. These families are alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, halogens, noble metals, and noble gases

Question 15

Identify an element as metal, nonmetal, or metalloid

Answer 15

Elements to the left of the line are considered metals. Elements just to the right of the line exhibit properties of both metals and nonmetals and are termed metalloids or semimetals. Elements to the far right of the periodic table are nonmetals. The exception is hydrogen (H), the first element on the periodic table

Question 16

List some properties of metals and nonmetals

Answer 16

Metals are defined as elements that possess properties such as , malleability, ductility, sonorous and good conductors of heat and electricity. While nonmetals are those elements that are not malleable, ductile, sonorous and are poor conductors of heat and electricity

Question 17

Define ion, cation, & anion

Answer 17

Cations are ions that are positively charged. Anions are ions that are negatively charged. Ions are charged atoms or molecules. If a balanced atom loses one or more electrons, it will become a positively charged cation. If a balanced atom gains one or more electrons, it will become a negatively charged anion

Question 18

Describe how cations and anions are formed (what do we change the number of

Answer 18

Ions are charged atoms or molecules. If a balanced atom loses one or more electrons, it will become a positively charged cation. If a balanced atom gains one or more electrons, it will become a negatively charged anion

Question 19

Identify the different types of radioactive decay (alpha, beta, gamma ray, positron, electron capture)

Answer 19

Alpha and beta decays almost always leave the nucleus in an excited state. Gamma emission brings the nucleus down to a more stable energetic state. Alpha and beta decays are often difficult to occur. They can be very slow processes.

Question 20

Fill in the blanks of a nuclear equation

Answer 20

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Question 21

Describe what must occur for an unstable nucleus to become more stable

Answer 21

The unstable nucleus of radioactive atoms emit radiation. When this occurs, a new atom and element are formed. This process is called radioactive decay. It continues until the forces in the unstable nucleus are balanced

Question 22

Describe what happens during a nuclear transformation

Answer 22

Nuclear Fusion reactions power the Sun and other stars. In a fusion reaction, two light nuclei merge to form a single heavier nucleus. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The leftover mass becomes energy

Question 23

Perform half-life calculations, including being able to determine how old a sample is given its half-life

Answer 23

Determine the original amount of the substance.
Determine the amount of time for which the substance was measured.
Determine the remaining amount of the substance after the time.
Substitute these values into the half-life equation and solve for half-life

Question 24

Describe the difference between nuclear fusion and nuclear fission

Answer 24

Fission is the splitting of a heavy, unstable nucleus into two lighter nuclei, and fusion is the process where two light nuclei combine together releasing vast amounts of energy

Question 25

List the pros and cons of nuclear fusion and nuclear fissio

Answer 25

Fission has fewer operating costs. This also reduces pollution and global warming. One of the disadvantages of fission is that fission when used in the generation of electricity produces uranium-235 which is a radioactive and extremely harmful waste product

Question 26

Generally describe how current nuclear power plants work

Answer 26

The water in the core is heated by nuclear fission and then pumped into tubes inside a heat exchanger. Those tubes heat a separate water source to create steam. The steam then turns an electric generator to produce electricity. The core water cycles back to the reactor to be reheated and the process is repeated

Question 27

List the applications of radioactivity in human society

Answer 27

Today, to benefit humankind, radiation is used in medicine, academics, and industry, as well as for generating electricity. In addition, radiation has useful applications in such areas as agriculture, archaeology (carbon dating), space exploration, law enforcement, geology (including mining), and many others

Question 28

Describe the penetrating power of alpha, beta, and gamma rays

Answer 28

Beta particles can partially penetrate skin, causing “beta burns”. Alpha particles cannot penetrate intact skin. Gamma and x-rays can pass through a person damaging cells in their path. Neutron radiation present during nuclear reactions, within a few miles of ground zero, is as penetrating as gamma rays

Question 29

Describe the 4 factors that affect how harmful radiation is to a living organism

Answer 29

The radiation could pass through the cell without damaging the DNA.
The radiation could damage the cell’s DNA, but the DNA repairs itself.
The radiation could prevent the DNA from replicating correctly.
The radiation could damage the DNA so badly that the cell dies

Question 30

Define vocab terms from Ch. 19

Answer 30

isotope: atoms with the same number of protons but different numbers of neutrons

nuclide:the general term applied to each unique atom; represented by , where is the symbol for a particular element

radioactivity: (radioactive decay) the spontaneous decomposition of a nucleus to form a different nucleus

beta particle: an electron produced in radioactive decay

nuclear equation: a representation of a nuclear reaction using atoms and atomic particles, including the atomic number and mass number, that shows the starting atoms and atomic particles along with the new atoms and atomic particles that are formed

alpha particle: a helium nucleus produced in radioactive decay

gamma ray: a high-energy photon produced in radioactive decay

positron: a particle that has the same mass as an electron but with a positive charge

electron capture: a process in which one of the inner-orbital electrons is captured by the nucleus of the atom

decay series: a series of nuclear decay processes that occurs until a stable nuclide is formed

nuclear transformation: the change of one element into another

half-life: the time required for half of the original sample of radioactive nuclides to decay