Periodic Table Trends Flashcards
Describe the periodic trends for atomic radius
- Atomic radius decreases from left to right across the periodic table.
- Atomic radius increases down the periodic table.
Describe the periodic trends for ionization energy
- First ionization energies increase from left to right across the periodic table.
- First ionization energies decrease down the periodic table.
First ionization energies ___ from left to right across the periodic table
Increase
First ionization energies ___ down the periodic table
Decrease
Describe the electronegativity of the atoms in a polar covalent bond
One atom in the bond must have higher electronegativity than the other atom
Define ionization energy
The amount of energy required to remove a valence electron from an atom
A more electronegative atom will have ___ attraction to the electrons in a chemical bond
More
Atomic radii decrease from left to right in a period (Na → Ar) on the periodic table.
Explain this trend
The nuclear charge increases in that direction
Elements that are most similar in their properties are found in the same _____
Group
_________ is a measure of an atom’s ability to attract electrons.
Electronegativity
Electronegativity ________ from left to right across a period on the periodic table and _______ from top to bottom of a group on the periodic table.
Increases, decreases
(follows the same trend as ionization energy)
Describe the periodic trends for atomic radius.
- Atomic radius decreases from left to right across the periodic table.
- Atomic radius increases down the periodic table.
Atomic radii decrease from left to right in a period (Na → Ar) on the periodic table. Explain this trend
- The nuclear charge increases in that direction.
- As the nuclear charge increases, all electrons in the outer shell (in this case the third shell) are attracted more strongly to the nucleus and are pulled closer to the nucleus.
Periodic trends in ionization energy
Exceptions in IE trend
What is electron affinity?
The ability of an electron (or ion) to gain electrons
When an atom gains an electron, energy is ___, so the ion is ___ stable than the atom
Energy is released, so the ion is more stable than the atom
What will happen if the electron affinity (EA) is positive?
The atom or ion tends to gain an electron and become more stable
What will happen if the electron affinity (EA) is negative?
The atom or ion does not tend to gain an electron
General trends in electron affinity
- Increases across a period
- Decreases down a group
What is electronegativity (χ)?
The ability of an atom in a molecule to attract shared electrons to itself
If a molecule has high electronegativity, it is an electron ___
Acceptor
If a molecule has low electronegativity, it is an electron ___
Donor
Periodic trend in electronegativity
What is atomic size?
The value of r below which 90% of electron density is conained
Periodic trend in Zeff
Increases across periodic table
Diagram showing PT trends in atomic radius
Explain how the size of ions differs from that of their neutral parent
- Cations (+) have radii that are smaller than their parent atom (makes sense cuz they lost an electron)
- Anions (-) have radii larger than their parent atom (gained electron)
What does it mean if two atoms or ions are isoelectronic?
They have the same electron configuration
What is the difference between electron affinity and electronegativity?
Electron affinity refers to the amount of energy released when a neutral atom gains an electron, while electronegativity describes an atom’s tendency to attract electrons within a chemical bond
