Periodic Trends

Periodic Trends All periodic trends can be explained by the atomic structure of an atom. The protons in the nucleus of an atom pull on the electrons. The number of electrons helps determine how an element behaves.

Atomic Radii decreases Atomic Radii _________across a period and _____________ down a group. As the atomic number increases across a period the positive nucleus has a _____________ attraction for the electrons. As you move down a group the electrons fill _____________ energy levels. The nucleus has a _____________ attraction for these electrons. increases stronger higher weaker

Valence Electrons Valence electrons are the number of electrons located in the _____________ and are available to be _____________, _____________, or _____________. The number of valence electrons _____________ across a period and __________ down a group highest energy level lost gained shared increases is the same

Ionization Energy Ionization energy is the energy needed to _____ an electron from an atom. The amount of energy as you move across a period and as you move down each group. As the atomic number increases across a period it takes _______energy to remove an electron because they are being held __________. As you move down a group the electrons are from the nucleus and it takes energy to remove them. remove increases decreases more tighter further less

Electron Affinity An atoms likelihood to gain an electron is measured by its ____. As you move across a period elements are likely to gain an electron. As you move down a group the atomic size which means the nucleus pulls less on the electrons and is less interested in gaining more. electron affinity more increases

Ionic Radii decreases Much like atomic radii, ionic radii across a period and _down a group. However, the size of a , or positive ion, is always _than an ___, or negative ion, since a positive ion ________electrons and a negative ion_______electrons. increases cation smaller anion loses gains

Ionic Radii (con’t) Since atoms either lose more electrons or gain less electrons as you go across a period, the nucleus has a ____ attraction for the electrons. As you go down a group the nucleus is attracted to the electrons in the higher energy levels since they are from the nucleus. stronger less further

Electronegativity Electronegativity is the ability for an atom to an electron in a bond. This property _ across a period since the atoms are in size and the nucleus is attracted to an electron. They are also to having 8 valance electrons in the outermost energy level. As you move down a group the electronegativity since the atoms are in size and the nucleus has a pull on an electron. attract increases smaller more closer decreases larger weaker

General Trends Increases Across Valence Electrons Ionization Energy Electronegativity Electron affinity - same - decreases - decreases - decreases

General Trends Decreases Across - increases - increases Atomic Radii Ionic Radii But cation < anion - increases

1. Atomic Radii Decreases Across Increases Down

2. Ionization Energy Increases Across Decreases Down

3. Electron Affinity Increases Across Decreases Down

4. Ionic Radii Decreases Across Increases Down ** Cations (left side, lose electrons) smaller than anions (right side, gain electrons)

5. Valence Electrons Increases Across SAME Down

6. Electronegativity Increases Across Decreases Down