Name: Periodic Table of Elements Block: The periodic table is a scientific work of art, hidden within it are multiple trends, groups, families, and patterns It took a few tries to get to this current masterpiece however Lavoisier, 1789, was the first to catalogue substances that could not be broken down any further o He included known elements, O, N, Hg, Zn, etc o He included light and caloric (heat) however Dobereiner began to group elements in triads according to similar properties in 1817 o Cl, Br, and I o Ca, Sr, and Ba o Li, Na, K A few other chemists began to notice trends over the next 40 years, but Mendeleev was the true periodic genius Dimitri Mendeleev was a Russian chemist who formulated a periodic table that is very similar to the one we use today o He grouped elements according to properties and atomic mass o He published this table in 1871 o He formulated the periodic law If the elements are arranged according to their atomic mass, a pattern can be seen in which similar properties occur regularly. o From looking at this we can see this is the current order of several elements in the periodic table today
The modern periodic law states: o If the elements are arranged according to their atomic number, a pattern can be seen in which similar properties occur regularly Element Families In the Periodic Table, columns are called groups or families of elements have similar properties o Group 1: o Group 2: o Group 3-12: o Group 17: o Group 18: Alkali Metals Group 1: Li, Na, K, Rb, Cs, Fr Have only one valence e -, are found in nature only as compounds, and are extremely reactive Remember when we put Na in water with Mr. E? Alkaline Earth Metals Group 2: Be, Mg, Ca, Sr, Ba, Ra Have two valence e -, found naturally as pure substances, react with water to produce alkaline (basic) solutions Be Mg Ca
Halogens Group 17: F, Cl, Br, I Have seven valence e At room temperature F and Cl are gases, Br is a liquid, and I is a solid, most reactive non-metals o Almost always found in nature as compounds Noble Gases Group 18: He, Ne, Ar, Kr, Xe, Rn All gases at room temperature, all have eight valence e -, a full valence shell and are therefore INERT o The full valence shell makes them very stable ( happy ), therefore they do not react with other elements Element Rows The horizontal rows of elements are called periods, o Ex: Row 1 is called 1 st period & it consists of H & He Atomic mass & atomic number increase from left to right Rare Earth Metals Rare earth elements or rare earth metals are a set of 17 chemical elements in the periodic table, specifically the fifteen Lanthanoids plus Sc and Y
Metals Lower left side of periodic table Characterized by their physical properties: o Solids and liquids at room temperature, shiny, malleable, ductile, and great conductors Non-Metals Upper-right hand side of periodic table (to the right of staircase) o Exception: H Non-metal that lives on the upper left corner of the periodic table Can behave as a metal or non-metal H + = metal H H - = non-metal H Characteristic physical properties of non-metals: o Solid, liquid, and gaseous, poor conductors, dull, brittle Graphite is pure carbon, where is graphite found? Semi-Metals Also called metalloids Elements that possess both metallic and non-metallic properties Found touching either side of the staircase o B, Si, Ge, As, Se, Te, Po Periodic Trends Atomic Size Atomic radii are used to measure the atomic size of elements Atomic size increases from top to bottom in elemental families and from right to left in each period As you move down a family or column more protons, neutrons and e - are added to the atoms so the radii increase as you move down As you move across a period the atomic radii decrease because the outer e - feel a greater attraction to the nucleus due to an increasing amount of protons
Ionization Energy The minimum amount of energy required to remove an electron from an atom o Increases from left to right because more and more protons are attracting e - o Decreases down a family because the outer most e - of larger atoms are not as attracted to the nucleus long distance relationships between p + and e - Metallic Properties Decrease from left to right and increase from top to bottom Valence Electrons Valence e - are important because they are the e - that form chemical bonds The number of valence electrons of an element is determined by its family (column) o Except for the transition metals, remember that they are special o They can have 3-12 valence e -