PERIODIC TABLE Flashcards
What is electronegativity
A measure of attraction, an atom has, for electrons or how badly the atom wants another electron. The higher the electronegativity, the more an atom wants an electron.
How is electronegativity a trend in the periodic table?
Electronegativity increases from left to right across a period.
Electronegativity decreases down a group.
When does an atom pull on an electron more and when does it pull on it less?
The closer the valence shell is to full, the stronger the pull of that atom on the
electrons in a bonding pair.
The further the valence electron shell is from the nucleus of an atom, the weaker the pull of the atom on the electrons in a bonding pair.
What type of atoms don’t attract electrons?
Noble gases have a complete valance shell so they do not attract
electrons.
What are the lanthanides and actinides electronegativity trends?
Lanthanides and actinides (the two rows of elements below the main table) have
complicated and weird chemistry, so they will not follow any trends.
Trends of transition metals electronegativity
They have low electronegativity this is because their metallic properties affect their ability to attract electrons as easily as the other elements
Metals VS Non metal electronegativity
Since metals have few valence electrons, they tend to increase their stability by losing electrons to become cations. Consequently, the electronegativities of metals are generally low. Nonmetals have more valence electrons and increase their stability by gaining electrons to become anions
Ionisation energy meaning
This is the amount of energy needed to pull an electron away from the atom in the gaseous state, or the tendency of an atom to give up electrons. This is conceptually the opposite of electron affinity.
What are the trends in first ionisation energy ONLY
o Increases from left to right across a period
- This is due to increasing effective nuclear charge
o Decreases from top to bottom down a group
- Because of electron shielding
o The noble gasses have very high first ionisation energy
- They have full valance shells
What is electron shielding? How does it affect ionisation?
Electron shielding is when the radius of an atom because big enough that the nucleus and the valence electron will lose their attraction. The higher the shielding effect the lower the ionisation energy
What is electron affinity
Electron affinity is the ability of an atom to accept an electron. This is a quantitative measurement of the energy change occurring when an electron is added to a neutral
gas atom.
Trends in electron affinity
Tend to be negative, meaning energy is released when the electron is added.
o The amount of energy released increases left to right across a period.
o The amount of energy released decreases down a group.
o The noble gases have positive first electron affinities, meaning they require energy to accept an electron.
What is an atomic radius
The atomic radius is one-half the distance between the nuclei of two atoms of the same
element.
Trends of an atomic radius
Increases right to left (backwards) across a period.
- Electrons are added left to right across a period to the same valance
shell. Simultaneously positive protons are added to the nucleus. The effect
of the positive protons is greater than the negative electrons, so there is a
higher effective nuclear charge. The nucleus attracts the electrons more
strongly, decreasing the atomic radius.
OR
Increases down a group.
- Valance electrons are added to shells further away from the nucleus. As shells are added, the outer electrons are shielded from nuclear attraction
from the inner electrons via electron shielding.
Metallic character trends
Metallic character decreases across a period.
- This is due to the increasing attraction between valence electrons and the
nucleus across the period.
OR
Increases down a group.
- This is because the atomic size is increasing, which causes the outer
electron shells to be farther away. This decreases effective nuclear
charge, making electrons to be lost more readily
