The Modern Periodic Table Chapter 5.2

Element Information in the Periodic Table Most often there are 4 pieces of information for each element listed on the periodic table.

Element Information in the Periodic Table Most often there are 4 pieces of information for each element listed on the periodic table. Atomic number (# of protons)

Element Information in the Periodic Table Most often there are 4 pieces of information for each element listed on the periodic table. Atomic number Element symbol (1st capital, 2nd small)

Element Information in the Periodic Table Most often there are 4 pieces of information for each element listed on the periodic table. Atomic number Element symbol Element name

Element Information in the Periodic Table Most often there are 4 pieces of information for each element listed on the periodic table. Atomic number Element symbol Element name Atomic mass

Atomic Mass Atomic mass depends on: Distribution of an element’s isotopes Masses of those isotopes. Isotopes = same element, different masses Masses different because: Same # protons Different # neutrons

Atomic Mass Atomic Mass Units 1 Atomic Mass Unit (amu) = Scientists chose one isotope to serve as a standard. This isotope is the most abundant one found in nature Carbon-12 atom: 6 protons and 6 neutrons. 1 Atomic Mass Unit (amu) = one twelfth the mass of a carbon-12 atom.

Most elements are mixtures of 2 or more isotopes. Atomic mass is weighted average. Example: Chlorine atomic mass = 35.453 amu. Two natural isotopes of chlorine: chlorine-35; chlorine-37 Chlorine-35: 17 protons and 18 neutrons. Chlorine-37: 17 protons and 20 neutrons.

The Periodic Law Elements in modern periodic table arranged by increasing atomic number (not mass) (Atomic number = # of protons). Periodic Law - Pattern of Repeating Properties Periods - Each row is a period. Each period is for a different electron shell or energy level

All of the Electron Shells

The Periodic Law Modern periodic table – stretched out (7 rows) Shows periods with Lanthanide & Actinide series where they really belong

The Periodic Law Elements are also arranged into vertical columns called Groups (or Families). Sounds of musical notes separated by an octave are related, but they are not identical. Properties of elements in a Group (column) are related, but not identical. Groups - Each column is a Group (or Family). Similar electron configurations Similar chemical properties

Example: Group 8A (or 18) - Noble Gasses with Full Shells Helium - Atomic #2 Neon - Atomic #10 Argon - Atomic #18

The Periodic Law Periodic Table of the Elements

Metals Largest class of elements on the Periodic Table - Metals. 80% of the elements.

Physical Properties of Metals Malleable and ductile (can change shape) Malleable = compress without breaking Ductile = stretch without breaking Good Conductors (thermal & electrical) Luster (means they are shiny!)

Transition Metals Groups 3 – 12: Form a bridge between elements on the left and right side of the table Tough, hard, and strong Less reactive than standard metals Have more properties in common than elements in other groups.

Metalloids Share characteristics of both metals & non – metals. Semi – conductors

Non-Metals Insulators (poor conductivity) Living organisms are mostly non-metals. (especially C, N, O, H) Most of the compounds in your body contain carbon

Variations Across a Period Across a period from left to right, the elements become less metallic and more nonmetallic in their properties. From left to right across Period 3, there are three metals (Na, Mg, and Al), one metalloid (Si), and four nonmetals (P, S, Cl, and Ar).

Variations Across a Period Sodium reacts violently with water. Magnesium will not react with water unless the water is hot. Aluminum does not react with water, but it does react with oxygen. Silicon is generally unreactive. Phosphorus and sulfur do not react with water, but they do react with oxygen. Chlorine is highly reactive. Argon hardly reacts at all.