Unit 8: Periodic Trends Flashcards
Row
Period
Properties of Valence Electrons (3)
- determines the chemical properties of the elements
- the electrons on the highest energy level
- are related to the group number of the element
Period
Row
Column
Group (not including transition elements)
What is the pattern of elements in the same group?
they both have the same number of valence electrons
What does the electron-dot symbol indicate?
the valence electrons as dots around the symbol of the element.
What does the electron-dot symbol show?
the number of valence electrons an element has
Relationship between elements of groups and electron-dot symbol
In a group, all the electron-dot symbols have the same number of valence electrons (dots).
ex) all elements in group 2 have 2 dots
The three periodic trends
Atomic Radius, Ionization E, Electron Affinity
Atomic Radius
actual size of atom measured from nucleus to valence e-’s
(Distance from nucleus to outermost shell)
Ionization Energy
Energy required to overcome the attraction from the nucleus and REMOVE an e-
Electron Affinity
potential energy change of the atom when an electron is added to a neutral atom to form a negative Ion
Shielding Effect
trends ACROSS the periodic table usually deal with electrons being added to the SAME energy level
trends DOWN a group usually deals with adding electrons to an INCREASING number of energy levels
Atomic Size
The distance from the nucleus to the valence electrons
How is atomic size described as?
by using the atomic radius
Patterns of Atomic Radius within a Group
atomic radius INCREASES when going DOWN a group
atomic radius DECREASES when going ACROSS a period
The element needs to be in what state for Ionization energy to occur?
gas
The _____ the radius is the _____ it is to remove an electron
bigger, harder
Ionization energies of metals are…
low
Ionization energies of non-metals are…
high
What does an increase in Ionization energy show?
tells that the element is taking on the electron configuration of the nearest noble gas
(breaking into a stable gas structure)
Metals are what kind of ion?
cation
Non-metals are what kind of ion?
anion
Positive Metal Cations are how large compared to the neutral atoms?
smaller than the neutral atoms from which they form from
Negative Nonmetal Anions are how large compared to the neutral atoms?
larger than the neutral atoms from which they form from
Electronegativity
ability of an atom to attract electrons from other atoms
The more ____ the electron affinity the more __ the electron addition process is
negative, favourable
What unit is electron affinity in?
kJ/mol
Electron Affinity Trend
Metals are LOW
Non-metals are HIGH
What letter is used for representative elements?
A
What are the representative elements?
elements from 1A to 8A
What elements does the A represent?
representative elements
What letter is used to represent transition elements?
B
What letter is B used to represent?
transition elements
Group numbers can also refer to (not a or b)…
the numbers in columns 1-18, left to right
What are representative elements known by?
common names
What common names do the groups go by?
1A - Alkali metals
2A - Alkaline-earth metals
3A-6A - No common names
7A - Halogens
8A - Noble Gas
Alkali Metals
Group 1A (1) which includes lithium, sodium, and potassium and forms a basic solution
Where are metals located?
left
Where are non-metals located?
right
Where are semi-metals located?
located along the heavy zigzag line between the metals and nonmetals
Properties of Metals
shiny and ductile (can bend into shapes)
are GOOD conductors of heat and electricity
Properties of Nonmetals
dull, brittle (crack/break easily)
POOR conductors of heat and electricity
Properties of Metalloids/Semimetals
BETTER conductors than non-metals, but NOT AS GREAT as metals
used as semiconductors and insulators
The metalloids section in the periodic table
B, Si, Ge, As, Sb, Te, Po, At
