Types of Periodic Trends Atomic Radii (AR) Ionization Energy (IE) Electronegativity (EN) Ionic Radii (IR) Metallic Charateristic (MC)

r – distance between particles Columbic Force Columbic Force (CF) (explanation for Periodic Trends) Opposite Charged Particles – Attract Same Charged Particles – Repel F = (Q1*Q2)/r Q1 – charge on particle 1 (nucleus “+” charge) Q2 – charge on particle 2 (valence e, “-” charge) r – distance between particles

Columbic Force – Periodic Trend Periodic Trend for Columbic Force (CF) Down a Group: Trend: Reason: Across a Period:

6.3 Trends in Atomic Size The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined. This diagram lists the atomic radii of seven nonmetals. An atomic radius is half the distance between the nuclei of two atoms of the same element when the atoms are joined.

6.3 Trends in Atomic Size This graph plots atomic radius versus atomic number for 55 elements. INTERPRETING GRAPHS a. Analyzing Data Which alkali metal has an atomic radius of 238 pm? b. Drawing Conclusions Based on the data for alkali metals and noble gases, how does atomic size change within a group? c. Predicting Is an atom of barium, atomic number 56, smaller or larger than an atom of cesium (Cs)?

6.3 Trends in Atomic Size The size of atoms tends to decrease from left to right across a period and increase from top to bottom within a group. Predicting If a halogen and an alkali metal are in the same period, which one will have the larger radius?

Atomic Radii (AR) Periodic Trend Periodic Trend for Atomic Radii (AR) Down a Group: Trend: Reason: Across a Period:

Trends in Ionization Energy 6.3 Trends in Ionization Energy Ionization Energy (IE) - The energy required to remove the first valence electron from an atom (atom is in the gas phase). What is holding the valence electron to the atom? Valence electron tightly held or loosely?

Trends in Ionization Energy 6.3 Trends in Ionization Energy

Trends in Ionization Energy 6.3 Trends in Ionization Energy

Trends in Ionization Energy 6.3 Trends in Ionization Energy First ionization energy tends to increase from left to right across a period and decrease from top to bottom within a group. Predicting Which element would have the larger first ionization energy—an alkali metal in period 2 or an alkali metal in period 4?

Ionization Energy (IE) Periodic Trend Periodic Trend for Ionization Energy (IE) Down a Group: Trend: Reason: Across a Period:

Ionization Energy (IE) Periodic Trends Two Exception to 1st Ionization Energy (IE) (Across the Period): 1. Be  B Trend: Reason: 2. N  O

Trends in Electronegativity 6.3 Trends in Electronegativity Trends in Electronegativity Electronegativity is the ability of an atom, in a chemical bond, to attract the shared valence electrons to itself. (i.e. the shared valence electrons are physically closer to the higher EN value atom than the other atom in the chemical bond). What EN really means? Fluorine?

Trends in Electronegativity 6.3 Trends in Electronegativity Representative Elements in Groups 1A through 7A

Electronegativity (EN) Periodic Trend Periodic Trend for Electronegativity (EN) Down a Group: Trend: Reason: Across a Period:

A cation is an ion with a positive charge. 6.3 Ions An ion is an atom or group of atoms that has a positive or negative charge. A cation is an ion with a positive charge. An anion is an ion with a negative charge.

6.3 Ions Metals elements lose valence electrons to form cation ions. Cation radii (IR) are always smaller than atomic radii (AR) [i.e. IR < AR] When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes?

6.3 Ions Non-metal elements gain valence electrons to form anion ions. Anion radii (IR) are always larger than atomic radii (AR) [i.e. IR > AR] When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes?

Relative Sizes of Some Atoms and Ions 6.3 Trends in Ionic Size Relative Sizes of Some Atoms and Ions This diagram compares the relative sizes of atoms and ions for selected alkali metals and halogens. The data are given in picometers. Comparing and Contrasting What happens to the radius when an atom forms a cation? When an atom forms an anion?

Trends in Ionic Size 6.3 Size generally increases Trends in Ionic Size The ionic radii for cations and anions decrease from left to right across periods and increase from top to bottom within groups.

Ionic Radii Periodic Trend Periodic Trend for Ionic Radii (IR) Down a Group: Trend: Reason: Across a Period: Metals large  small, then Non-metal large  small (Caution: Are not looking at same charge ion when across period) Metals: IR vs. AR : Non-metals: IR vs. AR :

Metallic Characteristics Periodic Trend Definition of Metals Composed of cations in a “sea” of free flowing valence electrons. Properties – Good Electrical Conductor Properties – Good Heat Conductor Properties – Malleable & Ductile Periodic Trends (Metallic Characterstic)