Chemistry I: Lesson 4 (Periodic Table)

Electronegativity is the ability of an atom in a molecule to attract electrons to itself

*https://www.khanacademy.org/science/biology/chemistry--of-life/chemical-bonds-and-reactions/v/electronegativity-and-chemical-bonds*

a stronger electrostatic pull toward the center of the atom *2.3 Chemistry*

As the positivity of the nucleus increases, the e' surrounding the nucleus, including those in the valence shell, experience________?

The more energy is required from an increasingly cationic (positive) species *2.3 Chemistry*

The more electrons are being removed from an electron the more _______ is required?

What does the 90 in Strontium-90 correspond with? A. Atomic Number B. Mass Number C. Atomic Weight D. Half Life

B. Mass Number, the 90 in strontium has to do with the mass number (protons + neutrons)

Periods- help determine the principle quantum number Groups-help determine the valence e' configuration *2.1 Chemistry*

Bridge: Quantum Numbers

Many transition metals act as cofactors (or coenzymes) for enzymes, including vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc. *2.4 Chemistry*

Bridge: Transition metals and Biochemistry

Because electron affinity is an exothermic process, ΔHrxn has a negative sign However electron affinity is reported as a positive number which refers to the energy dissipated *2.3 Chemistry*

Electron Affinity nomenclature

For example: An element in Group VA has 5 valence electrons with the configuration/s^2p^3/ *2.1 Chemistry*

For representative elements (ex: IA) the Roman numeral and the letter designation determine the electron configuration. Give an example.

the periodic table is organized based on increasing atomic number (# of protons) *2.1 Chemistry*

How is the periodic table arranged?

There are *7 periods*, each period represents quantum number n=1 through n=7 for the s- and p - block (ie: 7s , 5p) *2.1 Chemistry*

How many periods are there on the periodic table? What do these periods correspond with (quantum numbers)?

Periodic Trends Missing Electronegativity (down arrow) Electron affinity (down arrow) Note: Atomic radius is always opposite other trends. Ionic radius is variable *2.3 Chemistry*

Key Concept

when we perceive an object as a particular color, it because that color is not absorbed—but rather reflected—by the object. If an object absorbs a given color of light and reflects all others, our brain mixes these subtraction frequencies and we perceive the complementary color of the frequency that was absorbed. -For example: Carotene is a photosynthetic pigment that strongly absorbs blue light but reflects other colors. Thus, our brains interpret the color of carotene as the result of white light minus blue light, which is yellow light *2.4 Chemistry*

Key Concept: Additive and Subtractive Color Mixing

Yessir *2.3 Chemistry*

Key Concept: Electronegativity

True *2.2 Chemistry*

Key Concept: True or False? Alkali and Alkaline earth metals are both metallic in nature because they easily lose electrons from the /s/ subshell of their valence electrons

Elements with similar valence electron configurations generally behave in similar ways, as long as they are the same type (metal, nonmetal, or metalloid) *2.1 Chemistry*

MACT Expertise: Why is relating valence electrons to reactivity important?

*Electronegativity and and Ionization energy are related* the lower the ionization energy, the lower the electronegativity; the higher the ionization energy, the higher the electronegativity *2.3 Chemistry*

MCAT Concept: Electronegativity and Ionization Energies

Electron Affinity is essentially the opposite concept from ionization energy *2.3 Chemistry*

MCAT Concept: Ionization Energy and Electron Affinity

First ionization energy (IE) will always be smaller than second IE, which will always be smaller than third IE. However, the degree to which the IE increases provides clues about the identity of the atom. If losing a certain number of electrons gives an element a noble gas-like electron configuration, then removing a subsequent electron will cost much more energy. For example refer to the photo *2.3 Chemistry*

MCAT Expertise: Ionization Energy

For example: Chromium (/4s^1 3d^5/) and copper (/4s^1 3d^10/) *2.1 Chemistry*

Nonrepresentative elements may have unexpected electron configurations. Give an example.

Elements, esp. ones with biological roles, tend to be most stable with 8 e' in their valence shell *2.3 Chemistry*

Octet Concept

This increases the ionization energy *2.3 Chemistry*

The greater the atom's Z(eff) or the clser the valence electrons are to the nucleus, the more difficult it is to remove 1 or more e', this increases the what?

it attracts electrons within a bond

The greater the electronegativity of an atom , the more __________?

False, active metals are always found in ionic compounds, minerals, or ores *2.3 Chemistry*

True or false? Active metals are often found in their neutral forms

False, lithium is so reactive that it does not occur on earth inits elemental form, it is only found in various salt compounds. Lithium's elemental form is alkali earth metal *2.1 Chemistry*

True or false? Lithium is found in many places on earth in its elemental form? What is lithium's elemental form?

a) valence electrons b) positively charged nucleus *2.3 Chemistry*

What 2 factors effect Z(eff)?

metals, metalloids ( also called semimetals), and nonmetals *2.2 Chemistry*

What are the 3 categories of elements?

Many transition elements have 2 or more oxidation states (charges when forming bonds with other atoms) *2.2 Chemistry*

What are the characteristics of transition metals (Group B elements)?

-The electronegativities and ionization energies lie between those of metals and nonmetals *2.2 Chemistry*

What atomic characteristics do metalloids have?

1) have high ionization energies 2) high electron affinities 3) high electronegativities *all of these characteristics are the reasons why nonmetals do not easily give up electrons* *2.2 Chemistry*

What atomic characteristics do nonmetals exhibit?

1) has a low effective nuclear charge 2) low electronegativity( or high electropositivity) 3) large atomic radius 4) small ionic radius 5) low ionization energy 6) low electron affinity 7) good conductors of heat and electricity /all the characteristics allow metals to give up electrons easily/ *2.2 Chemistry*

What atomic characteristics does metals have (Hint: 7 characteristics)?

-have the classic physical properties of metals, except their densities are lower than those of other metals (ex: lithium) -Z(eff) values are *very low*, giving them the *largest* atomic radii of all the elements -Low Zeff value explains 2 other trends: *low* ionization energies, *low* electron affinities, *low* electronegativities -React readily with nonmetals-especially halogens *Due to their high reactivity with water and air, most alkali metals are stored in mineral oil* *2.4 Chemistry*

What characteristics do alkali earth metals (Group IA or Group 1) have?

-have many physical properties of metals -share most of the characteristics of alkali metals, excepts that they have slightly higher effective nuclear charges and slightly *smaller* atomic radii -Together alkali and alkaline earth metals are called the active metals because they are so reactive that they are naturally not found in their neutral (elemental) state *2.4 Chemistry*

What characteristics do alkaline earth metals (Group IIA or Group 2) have?

-Are an eclectic group of nonmetals and metalloids -Not as reactive as halogens -crucial for normal biological functions -Due to their proximity to the metalloids, they generally have *small* atomic radii and *large* ionic radii -Oxygen is the most important element in the group as it is one of the primary constituents of water, carbohydrates, and other biological molecules -Sulfur is also an important component of amino acids and vitamins -Selenium is also an important nutrient for microorganisms and has a role in protection from oxidative stress -*Note: At high concentrations many of these elements can be toxic and damaging* *2.4 Chemistry*

What characteristics do chalcogens (Group VIA or Group 16) have?

Groups have the same electronic configuration in their valence shell and share similar chemical properties *2.1 Chemistry*

What characteristics do groups share?

-are highly reactive nonmetals with 7 valence e', these elements are desperate to complete their octets by gaining 1 add'l e' -their physical properties are variable -At standard conditions, te halogens range from gaseous (F2 and Cl2) to liquid (Br2) to solid (I2) forms -Their chemical reactivity is more uniform and due to their *very high* electronegativities and *very high* electron affinities they are esp reactive toward alkali and alkaline earth metals -they are so reactive that they are not naturally found in their elemental state but rather as ions (called halides-or diatomic molecules) *Halogens are often tested on the MCAT* *2.4 Chemistry*

What characteristics do halogens (Group VIIA or Group 17) have?

-Aka inert gases because they have minimal chemical reactivity due to their valence shells -Have high ionization energies, meaning they have little to no tendency to gain or lose electrons (for He, Ne, and Ar, at least) -No measurable electronegativities (electronegativity is closest to 0) -extremely low boiling points and (therefore) exist as a gas at room temperature -Fun fact: have found a commercial niche as lighting sources due to their lack of reactivity) *2.4 Chemistry*

What characteristics do halogens (Group VIIIA or Group 18) have?

1) Lustrous (shiny) solid 2) generally have high melting points 3) High densities, excepts lithium (which has a density about half of H2O) 4) Are malleable, meaning can be hammered into shapes w/o breaking 5) have ductility, meaning they can be drawn or pulled into wires *2.2 Chemistry*

What characteristics do metals have? (Hint: 5 characteristics)

1) generally brittle in the solid state 2) show little or no metallic luster 3) poor conductors of heat and electricity 4) nonmetals are less unified in their chemical and physical properties than metals *2.2 Chemistry*

What characteristics do nonmetals have?

The Pauling electronegativity scale, which ranges from 0.7 for cesium, the least electronegative (most electropositive) element, to 4.0 for fluorine, the most electronegative element *2.3 Chemistry*

What is the most common scale to measure electronegativity?

the chemical and physical properties of the elements are dependent, in a periodic way, upon their atomic numbers *2.1 Chemistry*

What is the periodic law?

Z(eff) increases from left to right Z(eff) increases going to the right in the periodic table *2.3 Chemistry*

What is the trend of Z(eff) for elements in the same period? In the periodic table?

--have *low* electron affinities, *low* ionization energies, and *low* electronegativities -Physical properties: very hard and have high melting and boiling points, tend to be malleable, and are good conductors due to the loosely held e' that fill the d oribitals in their valence shells -*Unique property of transition metals*- they can have different possible charged form or oxidation states bc they are capable of losing different e' from the s and d orbitals in their valence shells For ex: Copper can exists as +1 or +2 oxidation state and Manganese can exists as +2, +3, +4, +6, or +7)-> this helps them to form many different ionic compounds -Solutions with transition metals are often colorful -They usually associate with molecules of water (called hydration complexes) or with nonmetals -> this ability to form complexes contributes to the variable solubility of certain metal-containing compounds (For ex: AgCl is insoluble in water but soluble in ammonia bc it forms [Ag(NH3)2]^+ -The formation of complexes causes the d orbitals to absorb certain frequencies of light -those containing the precise amount to raise e' from lower to higher energy d orbitals -> the frequencies not absorbed (called subtraction frequencies) give the complexes their characteristic colors *2.4 Chemistry*

What characteristics do transition metals have (Groups IB to VIIIB or Groups 3 - 12) have?

Their high potential energy and the fact that they are held less tightly by the nucleus *2.1 Chemistry*

What characteristics of valence electrons allows them to become involved in chemical bonds with valence electrons of other atoms?

An elements valence shell electrons *2.1 Chemistry*

What determines the chemical reactivity and properties of an element?

Periods correspond with rows Groups or families correspond with columns *2.1 Chemistry*

What do periods correspond with in the periodic table (rows or columns)? What do groups or families correspond with (rows or columns)?

More inner shells, the valence electrons will be found farther away from the nucleus *2.3 Chemistry*

What does a larger principal quantum number imply?

This causes the electron cloud to move closer and bind more tightly to the nucleus *2.3 Chemistry*

What does a stronger electrostatic pull do to an atom?

They have very high electron affinities because they need to gain only one electron to achieve the octet configuration of the noble gases *2.3 Chemistry*

What does that mean for group VIIA (in regards to electron affinity)?

They have very low electron affinities preferring to give up electrons to achieve the octet configuration *2.3 Chemistry*

What does that mean for groups IA and IIA (in regards to electron affinity)?

the number of valence electrons elements in that group have in their neutral state *2.1 Chemistry*

What does the Roman Numeral above each group (or column) represent?

Most metals have low electron affinity values

What does this diagram depict in terms of electron affinity?

Ionic Radii trend *Increases down and to the right* *2.3 Chemistry*

What does this diagram depict?

Ionization energy increases from left to right and within a *group* from bottom to top *2.3 Chemistry*

What does this diagram show in regards to first ionization energy and as a result the atoms themselves?

They have electron affinities on the order of 0 because the already possess a stable octet and cannot readily accept an electron

What electron affinities do noble gases have? Why?

Valence e' are separated from the nucleus by a greater number of filled principal energy levels, which can also be called inner shells. Result: the increased separation reduces the electrostatic attraction b/t the valence e' and the positively charged nucleus *2.3 Chemistry*

What happens as the principle quantum number increases?

Z(eff) is mitigated by nonvalence electrons that reside closer to the nucleus *2.3 Chemistry*

What is Z(eff) mitigated by?

Carbon, is a stereotypical nonmetal that retains a solid structure but is brittle, nonlustrous, and generally a poor conductor of heat and electricity *2.2 Chemistry*

What is a good example of a nonmetal?

it is the energy dissipated by gaseous species when it gains an electron it is an exothermic process bc it expels (or releases) energy *2.3 Chemistry*

What is electron affinity?Why is it considered an exothermic process?

Electronegativity is a measure of the attractive force that an atom will exert on an electron in a chemical bond

What is electronegativity?

the energy required to remove an electron from a gaseous species *2.3 Chemistry*

What is ionization energy or ionization potential?

Atomic Radii decreases left to right across a period -No, Atomic radius is essentially opposite that of all other periodic trends. Most increase going up and to the right, atomic radius increases going down and to the left *2.3 Chemistry*

What is the atomic radii trend? Is it comparable to any other trends?

one half of the distance between the centers of two atoms of *the same element* that are briefly in contact with each other *the atomic radius cannot be measured by examining a single atom bc the e' are constantly moving around, making it impossible to mark the outer boundary of the e' cloud*. *2.3 Chemistry*

What is the atomic radius of an element?

Atomic radius refers to the size of a neutral element , while an ionic radius is dependent on how the element ionizes based on its element type and group number *2.3 Chemistry*

What is the difference between atomic radius and ionic radius?

the effective nuclear charge (Z(eff)) Z(eff) measures the net positive charge experienced by the outermost electrons *2.3 Chemistry*

What is the electrostatic attraction between valence electrons and the nucleus known as? What does this term measure?

the second ionization energy X^2+

What is the energy necessary to remove a second electron from an atom called? What will the cation be written as now (Hint: You start with X^+)

first ionization energy *2.3 Chemistry*

What is the energy necessary to remove the first electron from an atom called?

Copper (Cu), Nickel (Ni), Silver (Ag), Gold (Au), and Platnium (Pt) -They are transition metals -These metalls' nonreactivity makes them ideal for the production of coins and jewelry *2.2 Chemistry*

What metals are relatively nonreactive? What type of metals are these? (Hint: Quarters)

Valence electron (the electrons in the last electron shell) *2.1 Chemistry*

What part of the atom is farthest from the nucleus and has the greatest amount of potential energy?

*Metalloids share some characteristics with both metals and nonmetals* -Make good semiconductors due to their partial conductivity of electricity -Metalloids densities, melting points, and boiling points vary widely and can be combinations of metallic and nonmetallic characteristics For ex: Silicon (si) has a metallic luster but is brittle and a poor conductor *the reactivities of the metalloids are dependent on the elements with which they are reacting* For ex: Boron (B) acts like a nonmetal when reacting with Sodium (Na) but like a metal when reacting with Fluorine (F) *2.2 Chemistry*

What physical characteristics do metalloids have?

Z(eff) remains constant The atomic radius increases down a group *2.3 Chemistry*

What remains constant down a period and increases down a period?

The s subshell *2.2 Chemistry*

What subshell are active metals' valence electrons found?

*s* and *f* subshells *2.2 Chemistry*

What subshell(s) are lanthanide and actinide series elements' valence electrons found?

*s* and *d* subshells *2.2 Chemistry*

What subshell(s) are transition metals' valence electrons found?

Metals *lose* electrons, *becoming more positive* Nonmetals *gain* electrons, *becoming more negative* Metalloids can *either gain or lose* electrons *2.3 Chemistry*

What trend do metals, nonmetals, and metalloids exhibit in terms of losing and gaining electrons?

Electronegativity increases across a period (from left to right) and decreases in a group from top to bottom *2.3 Chemistry*

What trend does electronegativity exhibit?

Metals are found on the left side of the periodic table and include 1) active metals 2) transition metals 3) lanthanide and actinide series of elements *in the picture they are colored* *2.2 Chemistry*

Where are metals found (and what do they include, hint: 3 types)?

They are predominantly found on the upper right side of the periodic table -highlighted in the picture *2.2 Chemistry*

Where are nonmetals primarily found?

Largest- Cesium (Note: Francium is typically not considered bc it is exceptionally rare in nature) Smallest-Helium *Atomic Radius increases down a period* *2.3 Chemistry*

Which atom has the largest atomic radius in the periodic table? Which atom has the smallest?

1. Boron (B), 2. Silicon (Si), 3. Germanium (Ge), 4. Arsenic (As), 5. Antimony (Sb), 6. Tellurium (Te), and 7. Astatine (At) *2.2 Chemistry*

Which elements are considered metalloids (8 elements)?

Because they have such low ionization energies, *meaning their atomic radii are large and their valence electrons are far from the nucleus in comparison to other atoms* *2.3 Chemistry*

Why are lithium and beryllium called active metals?

They already have a stable electron configuration and are unwilling to disrupt that stability by giving up an electron *Therefore noble gases are among the elements with the highest ionization energies* *2.3 Chemistry*

Why are noble or inert gases (Group VIIIA) the least likely to give up electrons?

This is because removing one electron from a Group IA metal results in a noble-gas like electron configuration *an atom would be happy in that state bc now it would have an empty electron shell* *2.3 Chemistry*

Why are the values of second ionization energies disproportionally larger for Group IA monovalent cations (like Na^+) but generally not that much larger for Group IIA or subsequent monovalent cations (like Mg^+)?

They rarely form bonds despite their high ionization energies *2.3 Chemistry*

Why do fluorine, bromine and chlorine have negligible electronegativity?

Metals closer to the metalloid line have more electrons to lose to achieve the electronic configuration seen in group VIIIA *Metals closer to group IA have fewer electrons to lose and therefore experience a less drastic reduction in radius during ionization* *2.3 Chemistry*

Why do metals close to the metalloid line have smaller ionic radii?

Because these nonmetals require more electrons than other nonmetals to achieve the electronic configuration seen in Group VIIIA *these nonmetals gain electrons while their nuclei maintain the same charge* These nonmetals include carbon, phosphorus, selenium, iodine, and radon *2.3 Chemistry*

Why do nonmetals close to the metalloid line have larger ionic radii than their counterparts closer to Group VIIIA?

-Because the stronger the electrostatic pull (the higher the Zeff) between the nucleus and the valence shell electrons, the greater the energy release will be when the atom gains the electron -Because the valence shell is farther away away from the nucleus as the principal quantum number increases *2.3 Chemistry*

Why does electron affinity increase from left to right and decrease from top to bottom?

Removing an electron from an atom *requires* the input of heat *2.3 Chemistry*

Why is removing an electron from an atom considered an endothermic process?

It separates elements into 2 larger classes. A elements are known as representative elements and include (IA through VIIIA) B Elements are known as non-representative elements and include both transition elements which have valence electrons in the s and d subshells *2.1 Chemistry*

Why would the Roman numeral above a group have a letter A or B next to it (ie: IIA or IIB)