Ch 25 Flashcards
Who published the first version of his periodic table, in which elements were ordered via atomic weight?
Dmitri Mendeleev
Henry Moseley organized elements based on
Atomic number
The periodic law states that
Chemical properties of the elements depend on their atomic number
There are seven periods (rows), each representing
The principal quantum numbers n = 1 to n = 7
Groups (columns) represent elements that have the same
Electronic configuration in their valence shell
The A elements are the
Representative elements
Representative elements have what as their outermost orbitals
Sublevels s and p
The B elements are non representative and fill orbitals
S, d, and maybe f
Transition elements have partly filled
D sublevels
Partly filled f levels are found in
Lanthanide and actinide series
From left to right across a period (row), the electrons experience
Nuclear attraction, becoming closer to the nucleus
What is the effective nuclear charge?
Net positive charge of the nucleus felt on electron
Down a given column, the outermost electrons become
Less tightly bound to the nucleus
The number of filled principal energy levels change how as you go downwards a group?
Increases
Zeff (effective nuclear charge) is at a maximum for elements
In the top-right of the table
Zeff (effective nuclear charge) is at a minimum for elements
In the bottom-left
Atomic radius increases
Right to left, and from up to down
The atoms with the largest radii will be located
Bottom of the groups and towards the left of the table
Something that affects the size of an electron will also
Change radius of an atom
The addition of protons increases from left to right across a period, leading to an increase in
Zeff (effective nuclear charge)
Valence electrons in higher energy shells will feel less pull become
Zeff becomes smaller with distance
What will be smaller, cations or anions?
Cations
What is Ionization energy?
Energy required to remove an electron from a gaseous atom or ion
Removing an electron requires an input of energy, meaning it is
Endothermic
What it the first ionization energy?
Energy required to remove one valence electron from the parent atom
What is the second ionization energy?
Energy needed to remove a second valence electron
Ionization energy increases from
Left to right across a period, and going up a group
Why do group 1a elements have low ionization energies?
The loss of an electron results in the formation of a stable, noble-gas configuration
What is the energy change that occurs when an electron is added to a gaseous atom, representing the ease by which atom can accept the electron?
Electron affinity
How is electron affinity when Zeff is high
Electron affinity is great
A negative electron affinity represents
Energy release
Why do Group VIIA elements, or halogens, have high electron affinities?
The addition of an electron results in a completely filled shell
What is the measure of the attraction an atom has for electrons in a chemical bond
Electronegativity
The greater an atom’s electronegativity, the greater its
Attraction for bonding electrons
The most common electronegativity scale is the
Pauling electronegativity scale, ranging from 0.7 to 4.0
Electronegativities are related to
Effective nuclear charge
Electronegativity increases from
Left to right, and down to up
What are the three categories of elements?
Metals, nonmetals, and semimetals
Metals have properties like:
- Large atomic radius
- Low ionization energy
- Low electronegativity
- Malleable
What is the ability to be drawn into wires called
Ductility
