UNIT 3 Part 3: The Periodic Table 1 Development of the Periodic Table 2 Reading the Periodic Table 3 Periodic Trends

1 Development of the Periodic Table Forerunners of the Periodic Table: Forerunners of the Periodic Table: As Chemists and other scientists discovered more and more Elements they needed a way to keep track of them all. They need a method of organization. As Chemists and other scientists discovered more and more Elements they needed a way to keep track of them all. They need a method of organization.

Döbereiner In the early 1800’s J.W. Döbereiner began classifying elements into groups of three (TRIADS ). The elements within the triads share similar chemical properties. In the early 1800’s J.W. Döbereiner began classifying elements into groups of three (TRIADS ). The elements within the triads share similar chemical properties. Ex:, lithium, sodium and potassium; calcium, strontium and barium; AND chlorine, bromine, and iodine are three sets of triads Ex:, lithium, sodium and potassium; calcium, strontium and barium; AND chlorine, bromine, and iodine are three sets of triads

Newlands Then in 1865, J.A.R Newlands noticed that when the known elements were arranged in, regular patterns would occur, AND they would repeat (law of octaves). Then in 1865, J.A.R Newlands noticed that when the known elements were arranged in increasing atomic mass, regular patterns would occur, AND they would repeat every 8 elements (law of octaves). C

Mendeleev & Meyer In 1869, Dmitri Mendeleev and Lothar Meyer independently published practically identical schemes for classifying elements. Mendeleev also noticed regular patterns in the elements when they were arranged by increasing atomic mass. He produced the first periodic table of elements and actually left spaced to be filled in by undiscovered elements. He was able to predict there would be more and about where they would go! In 1869, Dmitri Mendeleev and Lothar Meyer independently published practically identical schemes for classifying elements. Mendeleev also noticed regular patterns in the elements when they were arranged by increasing atomic mass. He produced the first periodic table of elements and actually left spaced to be filled in by undiscovered elements. He was able to predict there would be more and about where they would go!

Mendeleev's Periodic Table of the Elements

Periodic Law & Moseley The periodic table Mendeleev came up with was a good start but it wasn’t perfect. It wasn’t until 1913 when H.G.J. Moseley determined that the correct way to organize the periodic table is by. The when elements are The periodic table Mendeleev came up with was a good start but it wasn’t perfect. It wasn’t until 1913 when H.G.J. Moseley determined that the correct way to organize the periodic table is by ATOMIC NUMBER. The PERIODIC LAW- when elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern. Increases in atomic #

2 Reading the Periodic Table Organizing the Squares: Organizing the Squares: When you look at the modern Periodic Table of Elements (PTE) you will notice it is arranged in to columns (vertically) and rows (horizontally). The columns are called GROUPS or FAMILIES (18). The rows are called PERIODS (7). When you look at the modern Periodic Table of Elements (PTE) you will notice it is arranged in to columns (vertically) and rows (horizontally). The columns are called GROUPS or FAMILIES (18). The rows are called PERIODS (7). Periods GroupsGroups

Labeling & Naming Groups There are 3 methods for numbering the columns (the American, the European and the IUPAC) The only 2 your book uses is the American and the IUPAC. There are 3 methods for numbering the columns (the American, the European and the IUPAC) The only 2 your book uses is the American and the IUPAC. AMERICAN: 1A, 2A, 3B-8B, 11B, 12B, 3A-8A AMERICAN: 1A, 2A, 3B-8B, 11B, 12B, 3A-8A IUPAC: 1-18 IUPAC: 1-18 The families are given names: The families are given names: 1A- ALKALI METALS (except hydrogen) 1A- ALKALI METALS (except hydrogen) 2A-ALKALINE EARTH METALS 2A-ALKALINE EARTH METALS 7A- HALOGENS 7A- HALOGENS 8A- NOBLE GASES 8A- NOBLE GASES aka: inert or inactive gases

Metals, Nonmetals and Semimetals comprise the majority of the elements on the periodic table. Commonly they are solids (except Hg), malleable, conductors of heat and electricity, and are ductile. Also they have other specific physical properties such as luster or shine. Metals comprise the majority of the elements on the periodic table. Commonly they are solids (except Hg), malleable, conductors of heat and electricity, and are ductile. Also they have other specific physical properties such as luster or shine. comprise the second largest type of elements on the PTE. Many are also gases at room temperature (except bromine), which is a liquid. Nonmetals comprise the second largest type of elements on the PTE. Many are also gases at room temperature (except bromine), which is a liquid. have properties which are like metals but also like nonmetals. Theses comprise the smallest group on the PTE. Semimetals (metalloids) have properties which are like metals but also like nonmetals. Theses comprise the smallest group on the PTE.

Electronic Configuration & the PTE: The electrons in the outermost energy level are called the VALENCE electrons. The electrons in the outermost energy level are called the VALENCE electrons. These are the electrons which will allow one atom to interact with another atom and are responsible for the elements chemical properties. These are the electrons which will allow one atom to interact with another atom and are responsible for the elements chemical properties. The. The members in each group/family have the same # of valence electron and that is why they share similar chemical properties.

The s-, p-, d- and f-block Elements: S-BLOCK- groups 1&2 S-BLOCK- groups 1&2 P-BLOCK- groups P-BLOCK- groups D-BLOCK- groups 3-12 AKA: transition metals D-BLOCK- groups 3-12 AKA: transition metals F-BLOCK- the lanthanide & actinide series AKA: the inner transition metals F-BLOCK- the lanthanide & actinide series AKA: the inner transition metals S p d f

3 Periodic Trends As you move across the periodic table you begin to see trends/predictable patterns in the chemical and physical properties of the elements. This phenomenon is known as PERIODIC TRENDS. As you move across the periodic table you begin to see trends/predictable patterns in the chemical and physical properties of the elements. This phenomenon is known as PERIODIC TRENDS.

Atomic Radius Atoms have a radius called the ATOMIC RADIUS- the distance from the center of the atom to the farthest most/ highest energy level. This distance is not exact. We estimate. Atoms have a radius called the ATOMIC RADIUS- the distance from the center of the atom to the farthest most/ highest energy level. This distance is not exact. We estimate. Contrary to popular opinion… atoms with more electrons do not always have a larger atomic radius. The trend is: Contrary to popular opinion… atoms with more electrons do not always have a larger atomic radius. The trend is: As you move from TOP to BOTTOM down the PTE the radius grows larger As you move from TOP to BOTTOM down the PTE the radius grows larger As you move from RIGHT to LEFT across the PTE the radius grows larger As you move from RIGHT to LEFT across the PTE the radius grows larger

ATOMIC RADII Largest

The first trend has a simple explanation: as you move down through a group/family you are actually adding additional principle quantum numbers (ex group 1: 1s, 2s, 3s, 4s, 5s, 6s, and 7s) with corresponding increases in the number of electrons from 1, 3, 11, 19, 37, 55, and 87. Ergo the radius must increase to accommodate these increases in electrons. The first trend has a simple explanation: as you move down through a group/family you are actually adding additional principle quantum numbers (ex group 1: 1s, 2s, 3s, 4s, 5s, 6s, and 7s) with corresponding increases in the number of electrons from 1, 3, 11, 19, 37, 55, and 87. Ergo the radius must increase to accommodate these increases in electrons. The second trend is more complex. As you move across a period you are increasing both the # of electrons as well as the number of protons. in the same energy level thus. The second trend is more complex. As you move across a period you are increasing both the # of electrons as well as the number of protons. This allows the protons to pull more strongly on the electrons in the same energy level thus shrinking the radius.

Ionic Size We know atoms can gain or lose electron to form Ions. Depending whether they gain (becoming negatively charged) or lose (becoming positively charged) will depend on whether ionic size will shrink or grow. We know atoms can gain or lose electron to form Ions. Depending whether they gain (becoming negatively charged) or lose (becoming positively charged) will depend on whether ionic size will shrink or grow. When you gain electrons- the ionic size grows When you gain electrons- the ionic size grows As you lose electrons- the ionic size shrinks (more protons pulling on fewer electrons= shrinking). As you lose electrons- the ionic size shrinks (more protons pulling on fewer electrons= shrinking). The trend is complex- Figure 5-17 p.176 The trend is complex- Figure 5-17 p.176

Ionization Energy The energy needed to strip an atom of an electron is called IONIZATION ENERGY. Typically measured in J/atom you can think of it as a measure of how strongly the atom holds on to its valence electrons. The energy needed to strip an atom of an electron is called IONIZATION ENERGY. Typically measured in J/atom you can think of it as a measure of how strongly the atom holds on to its valence electrons. Its trend is exactly opposite the atomic radius trend: Its trend is exactly opposite the atomic radius trend: As you move from BOTTOM to TOP the ionization energy increases As you move from BOTTOM to TOP the ionization energy increases As you move from LEFT to RIGHT the ionization energy increases As you move from LEFT to RIGHT the ionization energy increases

Ionization Energy Hardest Easiest

Successive Ionization Energies What if you want to pull more than one electron from an atom? What happens to the ionization energy for the 2nd, 3rd, or even 4th electron? Successive ionization energies refer to the energy required to remove the 2nd, 3rd and more electrons. The energy required increases, partially because of electron-electron repulsion, however it is not a linear increase. Examine figure 5-20 p.180 Successive ionization energies refer to the energy required to remove the 2nd, 3rd and more electrons. The energy required increases, partially because of electron-electron repulsion, however it is not a linear increase. Examine figure 5-20 p.180 *note* there is always a dramatic increase in ionization energy when you start extracting electrons from the inner noble gas core. *note* there is always a dramatic increase in ionization energy when you start extracting electrons from the inner noble gas core.

Electron Affinity If you can pull an electron from an atom… you can ADD one to an atom. When an atom gains an electron energy is REQUIRED! They are reported in J/mol (NOT ATOMS). Not all energy used in the addition of an electron is gained by the atom that the electron is being added to. It is possible to have + and – electron affinities. If the value is + then the atom gaining the electron is also gaining energy. If the value is – then the atom gaining the electron is releasing energy. If you can pull an electron from an atom… you can ADD one to an atom. When an atom gains an electron energy is REQUIRED! They are reported in J/mol (NOT ATOMS). Not all energy used in the addition of an electron is gained by the atom that the electron is being added to. It is possible to have + and – electron affinities. If the value is + then the atom gaining the electron is also gaining energy. If the value is – then the atom gaining the electron is releasing energy.

General rule for the electron affinity trend- General rule for the electron affinity trend- Nonmetals have more NEGATIVE electron affinities than the metals. Nonmetals have more NEGATIVE electron affinities than the metals. The exception is the noble gases. The exception is the noble gases.. ** OCTET RULE** atoms tend to gain, lose or even share electrons in order to have a full set of valence electrons (8)- to have a full s and p orbital. More Negative

Electronegativity This is the ability of an atom to attract an electron in a chemical bond. This is a unit less value. This is the ability of an atom to attract an electron in a chemical bond. This is a unit less value. The least electronegative elements are in the LOWER LEFT CORNER of the PTE. The trend is the same as Ionization energy. The least electronegative elements are in the LOWER LEFT CORNER of the PTE. The trend is the same as Ionization energy. When bonds occur… the atom with the higher electronegativity would attract the electron more strongly. Depending on the discrepancy of the attraction there will form different types of bonds (Ch7). When bonds occur… the atom with the higher electronegativity would attract the electron more strongly. Depending on the discrepancy of the attraction there will form different types of bonds (Ch7).

More electronegative