Chapter 5 - The Periodic Law Flashcards
What is the name for repeating patterns?
Periodic
What is the periodic law?
The physical and chemical properties of the elements are periodic functions of their atomic numbers
How is the modern periodic table arranged?
In order of atomic number so that elements with similar properties fall in the same group
Group 1
- name
- outer electron shell description
- appearance
- reactivity
- exception
Alkali 1 electron in outer s orbital Silvery appearance and soft Very reactive Does not include hydrogen
Group 2
- name
- outer shell description
- reactivity
Alkaline-Earth
2 electrons in outer s shell
Less reactive than alkali, but still too reactive to be found pure in nature
What group number and type of electron shell does helium have?
Group 18 with two valence electrons in its filled outer shell, which gives it special chemical stability
What type of elements are in the d block?
Transition
What are the elements called in the s and p blocks?
Main-group
What three types fill the p block?
Non-metals, metals, metalliods
What are the group 17 elements called, how reactive are they, and what do they form when they do react?
Halogens, most reactive of all of the nonmetals, form salts
Where are the Metalliods?
Stair-step between nonmetals and metals
What is the first row under the periodic table called and what group can they be compared to in reactivity?
Lanthanides, group 2
What is the second row under the periodic table called and what is their special characteristic?
Actinides, all radioactive
Who made the very first periodic table and how was it arranged?
Mendeleev- by average atomic mass
How did Mendeleev know that his table was well-designed?
He predicted three elements that were discovered later (all before 1886). Ekaaluminum was Gallium, Ekaboron was Scandium and Ekasilicon was Germanium. He was able to predict many of their properties before they were discovered.
Who changed the first periodic table and how did he change it?
Mosely discovered that the elements fit better when arranged according to atomic number
What is the definition of the modern periodic table?
An arrangement of the elements in order of their atomic number so that elements with similar properties fall in the same column, or group
What are the differences in atomic number in a group? (group 18)
He-Ne-Ar-Kr-Xe-Rn is 8-8-18-18-32 (they represent the different sublevels that are being filled 8=sp 18=spd 32=spdf)
What are the general properties, name, and reactivity of the d-block elements?
Metallic properties, transition elements, low reactivity
What is group 18 called and how reactive are they?
Noble-gases, not reactive
How is the length of the period determined?
The number of electrons that can occupy the sublevels being filled in that period
What are the four blocks of the periodic table?
S, P, D, and F (they are determined by the sublevel being filled
What is the definition of atomic radius?
One-half the distance between the nuclei of identical atoms that are bonded together
What are the trends of the atomic radius in the periodic table + explain?
They increase as you go left and down
The size of the nucleus shrinks as you go right because more protons are being added which attracts the electrons (Zee effective charge) and they grow as you go down the table because the electron cloud is growing as sublevels are added
What is an ion?
An atom of group of bonded atoms that has a positive or negative charge
What is ionization energy (or first ionization energy)?
The energy required to remove one electron from a neutral atom of an element
What are the trends of ionization energy in the periodic table + explain?
They increase as you go right and up
The ionization energy increases as you go right because more protons are being added which attracts the electrons (Zee effective charge) and they grow as you go up the table because the electron cloud is shrinking as sublevels are removed (bigger cloud = easier to remove)
What is electron affinity?
The energy change that occurs when an electron is acquired by a neutral atom
What are the trends of electron affinity in the periodic table + explain?
They increase as you go right and up
The electron affinity increases as you go right because more protons are being added which attracts the electrons (Zee effective charge) and they grow as you go up the table because the electron cloud is shrinking as sublevels are removed (bigger cloud = easier to remove)
What is a cation?
A positive ion formed by the loss of one or more electrons
How does the formation of a cation change the atom (size) and why?
The atom (radius) shrinks; the remaining electrons are attracted more by the unbalanced positive charge
What is a anion?
A negative ion formed by the addition of one or more electrons
How does the formation of a anion change the atom (size) and why?
The atom (radius) grows; the greater electron repulsion causes the electrons to spread out more
What are the trends of ionic radius in the periodic table + explain?
They increase as you go left and down
The size of the nucleus shrinks as you go right because more protons are being added which attracts the electrons (Zee effective charge) and they grow as you go down the table because the electron cloud is growing as sublevels are added
What are valence electrons?
The electrons available to be lost, gained, or shared in the formation of chemical compounds
What is electronegativity?
A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound
What are the trends of electronegativity in the periodic table?
They tend to increase across periods and decrease or remain the same down a group
