Chemistry I H Ch. 6
elements past bismuth
(Bi), with atomic number 83 including 84 on, every isotope of each atom is radioactive (no stable isotopes past bismuth)
nonmetal solids
(below Br is solid) I, At, Se, S, P, C, Uus
octet rule
(elements' goal is to achieve octet rule) an atom with 8 valence electrons (s and p sublevel on highest energy level) is extremely stable and elements that satisfy this rule tend to be unreactive (do not combine to form compounds) in general (applies to helium)- an atom with a filled valence level (last energy level is full, not just the final sublevel) is extremely stable/unreactant (1s² is a full valence level because there is no possibility of a p sublevel or of having 8 electrons because p does not exist on the n=1 energy level)
Henry Moseley
(english physicist, 1913, x ray tube experiment, concluded that every element has a unique positive charge in its nucleus (unique number of protons- number of protons determines the identity of the element) (discovered that the atoms of each element contain a unique number of protons in their nuclei being equal to the atom's atomic number) arranged elements in increasing atomic number (Z) instead of increasing atomic mass - clear periodic pattern of properties corrected Mendeleev's work in early 1900s electron had been discovered, Rutherford-Bohr experiment had occurred says mass doesn't determine sequencing, atomic number (number of protons) does solved the reverse pairs problem periodic law (because atoms are electrically neutral, table arranged according to increasing number of electrons/electron configuration)
classification of the elements
3 main classifications for the elements metal, nonmetal, or metalloid
nonmetals
5 or more valence electrons (only 3 have less) carbon, helium, and hydrogen have less than 5 brittle (if solid) (break/shatter easily) dull surfaces (if solid) poor conductors of heat and electricity 1 liquid at room temperature (Br) nonmetal gases are noble gases, N, O, F, Cl, and H the rest of the nonmetals are dull, brittle solids
family names of metals
Alkali metals Alkaline earth metals Transition metals Inner transition metals
nonmetal liquid
Br- bromine
most reactive nonmetal
F (fluorine)
nonmetal gases
He, Ne, Ar, Kr, Xe, Rn, Cl, F, O, N, H (above Br is gas)
3 sets of reverse pairs
Iodine and tellurium (127 vs 128) Cobalt and nickel (58.9 vs 58.7) Argon and potassium (39.9 vs 39.1) elements lining up by properties but violating order of increasing atomic mass
Dimitri Mendeleev
Russian chemist known as the father of the periodic table 1860s took the known elements in his day and tried to put them into some order put in order of increasing atomic mass (before the electron was discovered) put elements with similar properties in the same group (column/family) problem: reverse pairs (demonstrated connection between atomic mass and elemental properties, noticed that when elements were ordered by increasing atomic mass, there was a repetition, or periodic pattern, in their properties) arranged elements in order of increasing atomic mass into columns with similar properties organized the first periodic table predicted the existence and properties of undiscovered elements and left blank spaces in the table where he thought the undiscovered elements should go not completely correct because several elements in his table were not in correct order- arranging the elements by mass resulted in several elements being placed in groups of elements with differing properties or vise versa
most important metalloids
Si, Ge 4 valence electrons just as easy to lose 4 and be like prior noble gas or gain four and be like subsequent noble gas "semi-conductors" -used in computer chips
actinide series
actinoids 5f sublevel 2 valence electrons ns²(n-2)f¹⁻¹⁴ (n=7, n-2=5) contains uranium (U)- last of the naturally occurring elements, with atomic number 92 every isotope is radioactive (no stable, non radioactive isotope in the f block/ inner transition metals)
Br
breakpoint between gas above, solid below
family names of nonmetals
chalcogens halogens noble gases
most compounds that contain transition elements are
colored (not white) ex- CrCl₃, Fe₂O₃ when you have unpaired electrons, leads to colored compound the more unpaired electrons you have, the harder the metal is (higher melting and boiling points)
transition metals
d block elements groups 3 through 12 2 valence electrons because ns² (n-1)d¹⁻¹⁰ (valence is p and s sublevels of highest energy level) variable oxidation numbers (lost all valence electrons first, also lose one or more d electrons possibly) (each element can have a range of possible oxidation numbers, but one makes it most stable- like noble gas) (or stops at half full d sublevel=intermediate stability) (after reaching octet with half full d sublevel, transition metals do not lose anymore d electrons- Fe only has 2+ and 3+ (more stable) states
stair-step line
divides nonmetals from metals metals to the left, nonmetals to the right (nm nature increases left to right, metallic nature decreases left to right, nm nature decreases right to left, metallic nature increases right to left) elements that border the line are the metalloids (not aluminum) visual divider between the metals and nonmetals on the table
valence electrons
electrons in the highest principal energy level of an atom (atoms in the same group have similar chemical properties because they have the same number of valence electrons) group number and number of valence electrons are related
metalloids
elements that have properties of both metals and nonmetals B, Si, Ge, As, Sb, Te, Po (7) positive and negative oxidation numbers (can form cations and anions) in some cases, act like metal and lose electrons (cation) in some cases, act like nonmetal and gain electrons (anion) behavior (cation or anion) depends on who reacting with reacting with nonmetal, metalloid acts like metal reacting with metal, metalloid acts like nonmetal semi-conductors
inner transition metals
f block elements f block has no group numbers lanthanide series actinide series
group aka
family vertical column 18 groups
nonmetals become like
following/subsequent noble gas by gaining electrons on the valence level (have electron configuration of noble gas but not identity- diff number of protons, atomic number determines identity)
how do nonmetals react
gain additional electrons on their valence level (trying to satisfy octet rule and be like noble gas) become anions- with negative oxidation numbers
metals
good conductors of heat and electricity malleable (can be hammered into thin sheets) ductile (can be drawn into a thin wire) luster (shiny when smooth and clean) 3 or less valence electrons in general (a couple of exceptions- BI (bismuth), Sn (tin), Pb (lead) if an element has two valence electrons, it is definitely a metal at room temperature (77° F, 25°C, 298 K), all metals are solid except for mercury, which is a liquid they react by losing valence electrons- metals form cations have positive oxidation numbers
chalcogens
group 16 only 3 of them 6 valence electrons bc ns² (n-1)d np⁴ oxidation number 2⁻ all of chalcogens have negative 2 oxidation number as anions but sometimes behave as if going to be positive always 2⁻ anions
halogens
group 17 7 valence electrons bc ns² (n-1)d np⁵ oxidation number 1⁻ contains some of the most reactive nonmetals- F is most reactive (sometimes chlorine can behave as if it is losing electrons- sharing) all of the halogens except fluorine will have other oxidation states but not behaving as anion (not gaining electrons) always 1⁻ anions
noble gases
group 18 8 valence electrons (except helium- 2 valence electrons) bc ns² np⁶ He- 1s² configuration all satisfy the octet rule, extremely stable and tend to be unreactive oxidation number is 0 (no combining capacity) (some scientists force fluorine and xenon to react and make compounds, but this is unnatural- often force noble gas Xe to react)
Alkaline earth metals
group 2 2 valence electrons because ns² oxidation number 2⁺ (elements are reactive if their electron arrangement is not like that of a noble gas)
isoelectronic
implies having the same electron arrangement/configuration
how did Mendeleev organize the periodic table
in order of increasing atomic mass (mass of an atom in amu) elements with similar properties in same groups (first useful and widely accepted periodic table)
elements past uranium
including 93, on all are synthetic or man-made elements
lanthanide series
lanthanoids 4f sublevel 2 valence electrons: ns²(n-2)f¹⁻¹⁴ (n=6, n-2=4) silver in color high melting points
which metal is not a solid at room temp
mercury liquid
Alkali metals
metals in group 1 (excluding hydrogen, a nonmetal) (hydrogen is in group 1 but not an alkali metal) 1 valence electron because ns¹ (ending of electron configuration) oxidation number 1⁺ (all want to be like noble gas in electron arrangement, do not equal noble gas because different number of protons- proton number determines identity of the element) (more reactive than alkaline earth metals- only need to lose one electron, combine easily with the extremely reactive halogens) (ions of an element have the same number of protons as neutral atoms)
anions
negative ions gain electrons negative oxidation numbers
other families without names
nitrogen family carbon family boron family
oxidation number of noble gases
none; 0
Hydrogen
nonmetal, not a metal still in group 1 (not alkali metal though)
cations
positive ions lose electrons positive oxidation numbers
metals become like
prior noble gas by losing electrons (have configuration of noble gas but not identity)
periodic function
properties will repeat after a certain number of elements
oxidation number
represents combining capacity (charge)
Moseley's periodic table
same column/group=similar chemical and physical properties because same number of valence electrons
helium
satisfies octet rule unreactive like all the other noble gases oxidation number is 0 valence level=1 entire valence level is filled (for metal like Be, not satisfied octet rule because has the possibility of a p sublevel on n=2)
another name for metalloids
semi-conductors or semi-metals have physical and chemical properties of both metals and nonmetals
period aka
series horizontal row 7 periods
Moseley's periodic law
the properties of the elements are a periodic function of their atomic number (Mendeleev-atomic mass) allowed for periods of different lengths (8, 18, and more) based on atomic number (Z)=number of protons= number of electrons therefore, arranged based on electron configuration (because atom is neutral) periodic law= the statement that there is a periodic repetition of chemical and physical properties of the elements when they are arranged by increasing atomic number the properties will repeat after a certain number of elements
the modern periodic table
the properties of the elements in the table repeat in a periodic way Mendeleev useful reference for understanding and predicting the properties of elements and for organizing your knowledge of atomic structure
reverse pairs
there are three sets of reverse pairs Te and I Co and Ni Ar and K masses violating sequence- wanted properties to line up, said masses might have error in determination, but iodine always less mass than tellurium elements lining up by properties but violating mass order Moseley corrected Mendeleev's work
