Electron Configuration & The Periodic Table. Unit 8, Chapter 5. Dmitri Mendeleev. A Russian chemist who hoped to organize the elements according to their atomic mass and properties
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Electron Configuration & The Periodic Table Unit 8, Chapter 5
Dmitri Mendeleev • A Russian chemist who hoped to organize the elements according to their atomic mass and properties • Periodic table – an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group
Henry Moseley • An English scientist who studied e-ray spectra of several elements in a row of the periodic table. • Found that each element had one more proton than the element immediately to its left. • Moseley’s discovery is the modern atomic number, not the atomic mass, is the basis for the organization of elements on the periodic table.
Periodic law – the physical and chemical properties of the elements are periodic functions of their atomic numbers. When elements are in order of increasing atomic number, elements with similar properties appear at regular intervals • According to the periodic law, the properties of elements can be predicted by their position on the periodic table
Alkali Metals • The elements of Group 1 of the periodic table (Li, Na, K, Rb, Cs, Fr) • Silvery appearance • Soft enough to cut with a knife • Very reactive, combining vigorously with most nonmetals
Alkaline-Earth Metals • The elements of Group 2 of the periodic table (Be, Mg, Ca, Sr, Ba, Ra) • Contain a pair of electrons in their outermost s sublevel • Harder, denser, stronger than alkali metals, higher melting points • Less reactive than alkali metals but still reactive
Hydrogen & Helium • Hydrogen does not have the same properties as elements in Group 1. • Hydrogen is a unique element with properties that do not closely resemble those of any group • Helium is a part of Group 18 because its highest energy level is filled by 2 electrons • Helium has stability , making it un-reactive like Group 18
d-Block Elements • Elements are metals with typical metallic properties and are often referred to as transition metals • Good conductors of electricity • High luster • Little reactivity
p-Block Elements • p-block elements together with the s-block elements are called main-group elements • p-block elements vary greatly in properties • The elements of Group 17 (F, Cl, Br, I, At) are known as halogens • Halogens are the most reactive nonmetals • Metalloids are the elements on the stair-step line • Metalloids have some characteristics of metals and some characteristics of nonmetals