Lesson outline Atomic size (radius) trends Ionization energy trends Ions Ions Electron affinity and electronegativity activity Electron affinity trends Electronegativity trends

Specific expectations B2.2 analyze data related to the properties of elements within a period to identify general trends in the periodic table. B3.3 state the periodic law, and explain how patterns in the electron arrangement and forces in atoms result in periodic trends (e.g., in atomic radius, ionization energy, electron affinity, electronegativity) in the periodic table.

Atomic size trends The atomic size (radius) is a measure of the size of an atom. Usually the typical distance from the center of the nucleus to the boundary of the surrounding cloud of electrons. ??????

Atomic size trends Increase in size from right to left: Elements on the right side of the periodic table have strong positive nuclei due to a higher number of protons in the nucleus. Resulting in a greater force of attraction between the protons and electrons, creating a smaller atomic radius. Increase in size from top to bottom: As elements proceed down the periodic table, they have more electrons, filling more electron energy shell, resulting in a larger atomic radius.

Ionization energy trend First ionization energy: The energy that is needed to remove the first electron from a neutral atom! Ion: a charged particle that results when a neutral atom gives up or gains an electron Cation (+): A positively charged ion resulting from an atom that gives away an electron Anion (-): a negatively charged ion resulting from an atom that gains an electron. Ex. O, Na, Cl

Ionization energy trend Increases from left to right: As you proceed from right to left, elements have a stronger positively charged nucleus (more protons) resulting in a greater force of attraction with the electrons. Increases from bottom to top: As you proceed up the periodic table, elements have less electron energy shells. Valence shell electrons have a stronger force of attraction with the nucleus because they are closer. Increases from bottom to top: As you proceed up the periodic table, elements have less electron energy shells. Valence shell electrons have a stronger force of attraction with the nucleus because they are closer.

Electron affinity trend Electron affinity: The change in energy that occurs when an atom gains an electron “An atoms desire to gain electron” Note: if energy is released when an atom gains an electron it is expressed as a negative integer. ??????

Electron affinity trend Increase from left to right: As you proceed to the right, elements have a stronger positive nucleus, resulting in a greater attraction for negative electron. This results in a larger net release of energy when an electron is added! Increases from bottom to top: As you proceed up, elements have fewer energy shells. There outer shell is closer to the positive nucleus, resulting in a greater attraction for electrons and a higher net release of energy

Electronegativity Electronegativity: refers to an atoms ability to attract/ pull electrons closer to its nucleus when in a chemical bond.

Electronegativity Increases from left to right: as you proceed to the right side of the periodic table, atoms have a stronger positive nucleus, resulting in a stronger force, pulling electron towards the nucleus. Increases from bottom to top: As you proceed up the periodic table, atoms have less energy shells. Therefore, the bonded (valence shell electrons) are closer to the nucleus, and experience a greater force of attraction.