1. Force of Attraction
- Definition: How much the outer electrons (-) are attracted to the nucleus (+)
- Increases going up periodic table because there is one fewer energy level of electrons that will separate the outer electrons from the nucleus
- Increases going right across periodic table because the
nucleus gains protons and the atom has the same number of energy levels as you move across a period
2. Shielding Effect
- Definition: How much the outer electrons are repelled by inner electrons (negative repels negative), and also describes how much control the nucleus has on outer electrons
- Increases going down periodic table because
there is an extra energy level of electrons that will shield the outer electrons from the nucleus
- Increases slightly going left on periodic table because the nucleus loses protons and the atom has the same number of energy levels as you move across a period
3. Atomic Radius
- Definition: A measure of a neutral atom’s size based on
the radius of its volume as a sphere
- Increases going down because there are more energy levels of electrons and therefore more shielding
- Increases going left because as you move across a period right-to-left, an atom loses a positively charged proton and therefore its electrons become slightly less tight and compact
4. Ionic Radius
- Definition: Same as atomic radius, but for the size of a charged ion, not a neutral atom
- Increases for anions (-) because they gain an electron, which leads to more shielding
- Decreases for cations (+) because they lose an electron, which means less shielding
5. First Ionization Energy
- Definition: The amount of energy needed to remove an outer electron from an atom and make it into an ion
- Increases going right because there are more protons in the nucleus pulling in electrons, so it requires more energy to remove an outer electron
- Increases going up because there are fewer energy levels and less shielding, so the
outer electrons are more tightly held by the nucleus
6. Metallic Character/Metallic Reactivity
- Definition: The tendency of an atom to lose an electron (a key characteristic of metals is they lose electrons to become cations)
- Increases going left because metals are on the left side of the periodic table and they have
fewer protons in their nucleus that are holding in the atom’s electrons
- Increases going down because there is more shielding, so outer electrons are easier to lose
7. Non-Metal Reactivity/Electron Affinity
- Definition: The tendency of an atom to gain an electron (a key characteristic of non-metals is they gain
electrons to become anions)
- Increases going right because non-metals are on the right side of the periodic table and they have more protons in their nucleus that attract outer electrons
- Increases going up because there are less electron energy levels and therefore a greater attraction to the nucleus for electrons
- ***Fluorine
has greatest non-metal reactivity because noble gases are not included due to the fact that they have a full shell of valence electrons and cannot gain more or react
8. Electronegativity
- Definition: The tendency of an atom to attract a shared electron in a chemical bond
- Increases going right because there are more protons in the nucleus
attracting outer electrons
- Increases going up because there are fewer energy levels of electrons shielding/repelling new outer electrons
- ***Fluorine has greatest electronegativity because noble gases are not included due to the fact that they have a full shell of valence electrons and cannot attract more
What are the major periodic trends?
Major periodic trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's properties.
What are 3 trends on the periodic table?
Major periodic trends include atomic radius, ionization energy, electron affinity, electronegativity, valency and metallic character. These trends exist because of the similar electronic configuration of the elements within their respective groups or periods and because of the periodic nature of the elements.
What are the 3 factors that influence periodic trends?
There are three factors that help in the prediction of the trends in the periodic table: number of protons in the nucleus, number of energy levels, and the shielding effect. The atomic radii increase from top to the bottom in any group. The atomic radii decrease from left to right across a period.
What do trends represent on the periodic table?
Answer: Periodic trends are specific patterns in the properties of chemical elements that are revealed in the periodic table of elements. Major periodic trends include electronegativity, ionization energy, electron affinity, atomic radii, ionic radius, metallic character, and chemical reactivity.