Chemistry Periodic Trends

Question 1

specific patterns in the periodic table that make it possible to make predictions about an element’s properties

Answer 1

periodic trends

Question 2

as the atomic number increases, the nuclear attraction for electrons increases, thus pulling the electrons in more tightly to the nucleus

Answer 2

Coulomb’s law

Question 3

one-half the distance between the nuclei of two identical atoms bonded together

Answer 3

atomic radius

Question 4

a measure of how readily an atom will react

Answer 4

reactivity

Question 5

when electrons in the inner energy levels block the attraction of the nucleus to the valence electrons

Answer 5

shielding effect

Question 6

a measure of the ability of an atom in a bond to attract electrons

Answer 6

electronegativity

Question 7

the energy required to remove one electron from a neutral atom of an element

Answer 7

ionization energy

Question 8

the charge of an ion

Answer 8

oxidation numbers

Question 9

the radius of a monoatomic ion in an ionic compound

Answer 9

ionic radius

Question 10

Summarize the connection between Coulomb’s law and the periodic trends.

Answer 10

This law explains why we see the trends we see in atomic radii, reactivity, electronegativity, etc. It is all about how tightly the electrons are being held to the nucleus, which is impacted by the number of protons in the nucleus, and the number of electrons both the total and specifically in the outermost energy level.

Question 11

Explain the following trends seen in the periodic table. Use a visual if it helps you explain the patters. Ionic radii:

Answer 11

Atoms that lose electrons become smaller
Atoms that gain electrons become larger
Tends to increase as you go DOWN a group

Question 12

Explain how the shielding effect works.

Answer 12

This occurs when electrons in the inner energy levels block the attraction of the nucleus to the valence electrons, and thus they become more loosely held.

Question 13

Describe how the difference in electronegativity between two atoms can be used to predict the type of bond that could form. Include an example to support your description.

Answer 13

EN shows if one atom will more strongly attract the electrons than the other. If the attraction is super strong (EN > 2), an ionic bond forms because one takes the electrons from the other. If the attraction is very low (EN < 0.5), a covalent bond forms and the electrons are mostly equally shared. If EN is somewhere in the middle, a polar covalent bond is formed where electrons are unequally shared.
Ex. Atmospheric nitrogen (N2) makes an EN = 0, thus a covalent bond will form and electrons will be equally shared.

Question 14

Identify the oxidation numbers for elements in groups 1, 2, and 13-17.

Answer 14

Group 1 - +1
Group 2 - +2
Group 13 - +3
Group 14 - +/-4
Group 15 - -3
Group 16 - -2
Group 17 - -1

Question 15

Be able to make distinctions between elements using the periodic trends when given a model, description, or example.

Question 16

Be able to make predictions about how main group elements will behave based on their location on the periodic table.

Question 17

Be able to calculate the difference in electronegativity between two atoms and use it to predict the type of bond that would form.

Question 18

Be able to identify a cation or anion based on a picture, description, or example.

Question 19

Explain atomic radius:

Answer 19

the atomic radius can be determined by measuring the distance between two adjoining nuclei in a molecule comprised of two identical atoms, and then dividing two.
For nonmetallic atoms that do not form diatomic molecules, the radius is determined by measuring the radius of atoms in covalent compounds.
For metallic atoms, the radius is determined by measuring the radius of atoms in metallic crystals.
The Periodic Trends Gizmo uses calculated atomic radii established by Enrico Clementi and others in 1967.

Question 20

Explain Ionization Energy:

Answer 20

ionization energy refers to an atom’s tendency to hold on to its electrons.
the lower an atom’s ionization energy, the more likely that atom is to lose electrons
he first ionization energy is the energy needed to remove a single valence electron from an atom, the second ionization energy is the energy required to remove an additional valence electron, etc. ionization energy increases with the removal of each successive electron

Question 21

Explain Electron Affinity:

Answer 21

electron affinity refers to the tendency of an atom to attract electrons.
an element with a strong attraction for electrons will have a high negative electron affinity, since energy is released when an electron is added. the greater the magnitude of the negative electron affinity value, the stronger the attraction for electrons

Question 22

Explain electron cloud:

Answer 22

the electron cloud can be considered a probability distribution representing the space where electrons are most likely to be found

Question 23

Explain energy level:

Answer 23

the number of principal energy levels within an atom is equal to that atom’s period number on the periodic table.
there are a maximum of 7 principal energy levels within an atom

Question 24

explain a group:

Answer 24

groups are also called families.
elements in the same group have the same number of valence electrons and similar chemical properties

Question 25

explain an ion

Answer 25

an atom with more protons than electrons is a positively charged ion, or cation
an atom with more electrons than protons is a negatively charged ion, or anion
in an element symbol, the electric charge is a shown as a superscript at the upper right. For example, Be2+ is an ion of beryllium with a charge of positive 2

Question 26

explain metal

Answer 26

metal atoms tend to hold electrons loosely
metal atoms tend to lose electrons, forming positive ions
metals typically have a low ionization energy and a low electron affinity

Question 27

explain nonmetal

Answer 27

nonmetal atoms tend to hold electrons tightly
nonmetal atoms tend to gain electrons, forming negative ions
nonmetals typically have a high ionization energy and a high electron affinity

Question 28

explain nucleus

Answer 28

the total number of particles (protons and neutrons) in the nucleus is given by the atom’s mass number
the nucleus contains over 99.9% of an atom’s mass, but onlu occupies about 1/100,000 of its volume

Question 29

explain period

Answer 29

elements within the same period share the same number of principal energy levels

Question 30

unit of length used to measure atomic radius that is equal to one-trillionth (10^-12) of a meter

Answer 30

picometer

Question 31

an electron found in the outermost energy level of an atom

Answer 31

valence electron