Chem Unit 3 Flashcards
A period is:
a horizontal row
A group/family is:
a vertical column
Electronegativity increases as you go:
Up and right across the periodic table
Why does electronegativity increase?
(Left to right) If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one.
From top to bottom down a group, electronegativity decreases. This is because atomic number increases down a group, and thus there is an increased distance between the valence electrons and nucleus, or a greater atomic radius.
What is electronegativity?
Electronegativity can be understood as a chemical property describing an atom’s ability to attract and bind with electrons. Because electronegativity is a qualitative property, there is no standardized method for calculating electronegativity.
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What is ionization energy?
Minimum energy required to remove an electron from an atom
Ionization energy increases as you go:
Up and right across the periodic table
Why does ionization energy increase?
the minimum energy required to remove the most loosely bound electron of an isolated gaseous atom, positive ion, or molecule.
(Left to right) More protons makes it harder to pull electrons away from atoms
(Bottom to top) Outermost electrons of small atoms are closer to the nucleus and more tightly held
What is electron affinity?
Electron affinity is how much energy is released when an electron is added to a nucleus. Halogens have high electron affinity.
Electron affinity increases as you go:
Up and right across the periodic table
Why does electron affinity increase?
(Left to right) Electrons are closer to the nucleus, increasing energy released
(Up to down) Outermost electrons are more tightly held in small atoms, releasing more energy than big atoms.
Atomic radius down = electron affinity up
What is atomic radius?
The atomic radius is one-half the distance between the nuclei of two atoms.
Atomic radius increases as you go:
Left and down across the periodic table
Why does atomic radius increase?
(Left to right) Less protons in a row = weaker force of attraction
(Up to down) More shells being added around the nucleus
What is metallic character?
The metallic character of an element can be defined as how readily an atom can lose an electron.
Metallic character increases as you go:
Down and left across the periodic table
Why does metallic character increase?
(Left to right) More valence electrons makes it harder to lose electrons.
(Up to down) Valence electrons getting further away from the nucleus in large atoms makes it easier to lose an electron.
