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Flashcards in Periodic Table & Trends Deck (29):
1

What are the two major factors that contribute to periodic trends?

1. As you move from left to right, effective nuclear charge increases
2. As you move from top to bottom, radius of the valence shell increases moving further away from the nucleus

2

Which periodic trends are determined by effective nuclear charge?

1. Ionization energy
2. Atomic radius
3. Electron affinity

3

What is the atomic radius its trend?

Distance from center of nucleus to exterior of valence electron cloud. Radius decreases as you move up and to the right

4

What is ionization energy, its units, and its trend? How is its trend different?

Ionization energy is the energy measured in kJ/mol required to remove the outermost electron from an atom. It increases as you move up and to the right. Compared to electronegativity, ionization energy trend is very erratic because it accounts for half-filled and filled orbital stability

5

What is electron affinity, its units, and its trend?

Electron affinity is the energy (kJ/mol) absorbed (endothermic) or released (exothermic) when an electron is added to the valence shell of an atom. It increases as you move up and to the right

6

What is electronegativity and its trend?

Electronegativity is the willingness of an atom to gain and retain an electron from a neighboring atom in a covalent bond. It increases are you move up and to the right

7

What is the general principle behind the exceptions to the general trends? What two trends do they effect?

Half or completely filled subshells - electron affinity and ionization energy

Column with nitrogen vs. column with oxygen: nitrogen has all of its p orbitals half-filled, therefore, it requires greater energy to remove an electron (ionization energy) and when an electron is added less energy will be given off, if any (electron affinity)

8

What is the general rule regarding the atomic size of cations and ions?

Generally, cations are smaller than neutral and anions due to less electron repulsion. Anions are larger than neutral atoms and cations due to greater electron repulsion

9

What has a greater atomic radius, hydrogen or helium?

Hydrogen has smaller radius. The electrons in the helium atom are so close together that it causes repulsion

10

What is the relationship between bond length and atomic radius?

The more tightly held the valence electrons are to the nucleus (shorter atomic radius) the shorter the bond will be between two atoms. Shorter bonds are stronger bonds

11

What are the two exceptions to ionization energy?

Half or completely filled subshells

12

What is the relationship between ionization energy and oxidation/reduction potentials?

MORE NEEDED ON THIS

13

Why is second ionization energy always greater than first ionization energy?

Electrostatics - removal of second electron is more difficult due to stronger

14

Higher electron affinity is associated with a more negative or positive energy?

Negative energy. A higher affinity means that the atom becomes more stable upon an addition of an electron to its valence shell, thereby releasing more energy (exothermic). Higher electron affinity is associated with a more negative energy

15

How is electronegativity measured? How is bond determined to be ionic or covalent?

Pauling Scale is measured from 0.9 for Na and 4.0 for F. A bond is determined to be ionic if the electronegativity difference of the atoms is greater than 2.0 and covalent if less than 2. For those bonds that are between 2 and 1.5, they are said to be polar covalent. Below 1.5 is nonpolar covalent

16

How is chemical reactivity of an atom determined?

Atoms of the same family (column) have similar reactivity because they have the same valence electrons

17

What is the name of the family containing oxygen

Chalcogens

18

Why are alkali metals strong reducing agents?

By losing their only valence s electron, they obtain a complete octet, stabalizing the atom.

19

Why does the reactivity differ between alkali metals? In presence of molecular oxygen, what effect do the differences of reactivity have on the formation of oxides?

Ionization energy decreases as more shells are added to an atom. As you move down the alkali family, its easier to lose an electron thus becoming a more reactive species. As you move down the family/group, the elements become more corrosive/susceptible to oxidation. This can be seen by the different oxide formations and the stoichiometric relationships in the reactions.

20

What is the product of mixing solid alkali metal and water?

Metal hydroxide + hydrogen gas

21

What are the three different oxides that alkali metals form and why do they differ?

1. 4 Lithium atoms + 1 molecule O2 --> 2 molecules Li2O(s) [oxide[

2. 2 Sodium atoms + 1 molecule O2 --> 1 molecule Na2O2 [peroxide]

3. 1 K, Rb, Cs(s) atom + 1molecule O2 --> MO2 [superoxide]

22

Why would diatomic nitrogen corrode lithium metal moreso than diatomic bromine?

Diatomic nitrogen has a stronger reduction potential than bromine does. This is required because, relative to the elements down the alkali family, lithium does not have a strong oxidation potential, requiring a species with a strong reduction potential in order for the reaction to occur.

23

For bromine to become reduced, which metal would be the better reducing agent?

Because bromine's reduction potential is not that strong relative to the other halogens, it requires a metal with a strong oxidation potential. Oxidation potential increases as you move down the alkali metal family. Cesium is stronger than Rubidium and Potassium in terms of oxidation potential. Therefore, for bromine to react, Cesium would be the best choice.

24

Of the alkali metals, which are the stronger reducing agents?

The oxidation potential increases as you move down the alkali family due to increase shielding

25

What is the solubility of alkali and alkaline earth metals in water?

Alkali metals are soluble in water but alkaline earth metals are not.

26

How do alkaline earth metals compare to alkali metals in terms of reactivity/oxidation?

Alkaline earth metal have the same trends as alkali metals but are not as strong as reducing agents due to their stronger effective nuclear charge. Comparing elements of the same period, the alkaline earth metal will have a lesser oxidation potential

27

What is unique about beryllium?

Berylllium forms covalent bonds not ionic bonds due to their small size and effective nuclear charge

28

Chalcogens are consisted of what types of elements? What is the reactivity trend of this elements? Solubility?

Nonmetals and metalloids. Oxygen and sulfur are nonmetals whereas selenium, tellurium, and polonium are metalloids. Reactivity decreases as you move down the family. They are usually nonsouble in water

29

How do the chalcogens exist in nature? What is their structure? Are they all diatomic?

Oxygen exists in a diatomic state. Sulfur and Selenium exist in an octameric state, telenium and polonium exist in molecular matrices