Periodic Table Trends

Russian scientist and professor Mendeleev (1870) Russian scientist and professor Arranged the 63 elements by atomic mass Noticed a repetition of properties (periodicity) Called the pattern of properties “Periodic Law” Mendeleev (correctly) predicted the mass of elements yet to be discovered and left spaces open for them

Repetition of properties (periodicity) became more clear Moseley (1913) Experiments showed proton number was a better method to organize the elements. Repetition of properties (periodicity) became more clear Modern Periodic Law: “The properties of elements are a periodic function of increasing atomic number” We know now that most element properties are due to the number of valence electrons

An updated Periodic Table containing ALL 118 elements – separated into metal and non-metal atoms make up EVERYTHING in the Universe.

Element with properties opposite to those of metals (brittle, dull…) Rows of the periodic table are called periods. Elements in periods do not have similar properties Left to right Elements change from metals to non-metals Non-metal Element with properties opposite to those of metals (brittle, dull…) periods

Family names and locations need to be memorized Columns of the periodic table are called groups. Elements in groups have similar properties A family is a group with a specific name: Family names and locations need to be memorized GROUP Alkali metals Alkaline Earth metals Chalogens Halogens Noble (inert) gases

(make coloured compounds, speed up chemical reactions…) Transition Metals: groups 3 – 12 unique properties different from group 1 and 2 metals (make coloured compounds, speed up chemical reactions…)

Simplest atomic structure - only 1 e- and 1 p+ Hydrogen* Group 1 Non-metal gas 1 valence electron Simplest atomic structure - only 1 e- and 1 p+ Highly chemically reactive The placement of hydrogen is only because of its structure - 1 proton… Sometimes a table will have it raised above the Alkali Metals to avoid confusion

Increasing Reactivity The LESS electrons needed, the GREATER the chemical reactivity of the element Increasing Reactivity

CAN YOU ANSWER THESE QUESTIONS? S1-2-06 How is the Periodic Table organized for the elements and what trends exist? Vocabulary & Concepts  Mendeleev Period Group Family Alkali metals Earth metals Transition Metals Chalcogens Halogens Noble gases

IONS IONS are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom gives a CATION with a positive charge Adding an electron to an atom gives an ANION with a negative charge. To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na+ Ca+2 I- O-2 Na Ca I O

Forming Cations & Anions A CATION forms when an atom loses one or more electrons. An ANION forms when an atom gains one or more electrons F + e- --> F- Mg --> Mg2+ + 2 e-

PREDICTING ION CHARGES In general metals (Mg) lose electrons ---> cations nonmetals (F) gain electrons ---> anions

Learning Check – Counting State the number of protons, neutrons, and electrons in each of these ions. 39 K+ 16O -2 41Ca +2 19 8 20 #p+ ______ ______ _______ #no ______ ______ _______ #e- ______ ______ _______

One Last Learning Check Write the nuclear symbol form for the following atoms or ions: A. 8 p+, 8 n, 8 e- ___________ B. 17p+, 20n, 17e- ___________ C. 47p+, 60 n, 46 e- ___________

Charges on Common Ions -3 -2 -1 +1 +2 By losing or gaining e-, atom has same number of e-’s as nearest Group 8A atom.