Chemistry chapters 5 and 6
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83 Terms
Who developed the concept of Triads?
Dobereiner developed the concept of Triads based on properties.
Who arranged elements by atomic mass and defined the Original Periodic Law?
Meyer and Mendeleev arranged elements by atomic mass and grouped them by properties.
Who created the Original Periodic Law (1860s)?
Lothar Meyer and Dimitri Mendeleev.
How were elements arranged in the Original Periodic Law?
Elements were arranged according to atomic mass.
How were elements grouped in the Original Periodic Law?
Elements were grouped based on similarities in their properties.
Who developed the Modern Periodic Law?
Henry Moseley (1887–1915).
How are elements arranged in the Modern Periodic Law?
Elements are arranged by their atomic number.
What is the definition of the Periodic Law?
When elements are arranged in order of increasing atomic number, elements with similar chemical and physical properties appear at regular intervals.
What do periods (horizontal rows) indicate?
The highest occupied energy level (PEL) of an element.
What do all elements in the same period have in common?
The same number of electron shells.
What do groups (vertical columns) indicate for representative elements?
The number of valence electrons.
Why do elements in the same group share similar chemical properties?
They have the same number of valence electrons.
What are valence electrons?
Electrons in the highest occupied energy level (outermost shell).
Why are valence electrons important?
They determine bonding and chemical properties.
In which sublevels do valence electrons exist?
Only in the s and p sublevels.
For representative elements, what does the group number indicate?
The number of valence electrons.
Where are metals located on the periodic table?
Bottom left.
What is the typical state of metals?
Solid (except mercury).
What are key properties of metals?
High luster, malleable, ductile, good conductors, easily lose electrons.
Where are nonmetals located on the periodic table?
Top right.
What is the typical state of nonmetals?
Gases, molecular solids, or network solids (except bromine).
What are key properties of nonmetals?
Dull, brittle, poor conductors, high electronegativity and ionization energy.
Where are metalloids located?
Along the boron staircase.
What defines metalloids?
They have properties of both metals and nonmetals and are semiconductors.
What elements are classified as metalloids?
Boron, Silicon, Germanium, Arsenic, Tellurium, Antimony.
What are Representative Elements?
Group A elements composed of the s and p block.
How many valence electrons do Group 1 elements have?
1 valence electron.
What are Group 1 elements called?
Alkali Metals.
What are the properties of Alkali Metals?
Very reactive, easily lose electrons, not found pure in nature.
What are Group 2 elements called?
Alkaline Earth Metals.
What are the properties of Alkaline Earth Metals?
Easily lose electrons and are very reactive.
How many valence electrons does Group 15 have?
5 valence electrons.
How many valence electrons does Group 16 have?
6 valence electrons.
What are Group 17 elements called?
Halogens.
What are the properties of Halogens?
Highly reactive, 7 valence electrons, exist as diatomic molecules.
What are Group 18 elements called?
Noble Gases.
What are the properties of Noble Gases?
Inert, stable monatomic atoms with full octets (except He).
What defines Transition Metals?
Last electron in the d sublevel and form colored ions.
What defines Inner Transition Metals?
Last electron in the f sublevel; lanthanide and actinide series.
What is nuclear charge?
The positive charge of the nucleus due to protons.
What is the shielding effect?
Inner electrons reduce attraction between the nucleus and outer electrons.
What causes increased shielding?
More electron shells.
What is atomic radius?
Distance from the atom center to the electron cloud boundary.
How does atomic radius change across a period?
It decreases.
How does atomic radius change down a group?
It increases.
What is ionization energy?
Energy required to remove an electron.
How does ionization energy change across a period?
It increases.
How does ionization energy change down a group?
It decreases.
What is electronegativity?
The desire of an atom to attract electrons.
How does electronegativity change across a period?
It increases.
How does electronegativity change down a group?
It decreases.
What is ionic radius?
The size of an ion.
What happens to atomic size when a cation forms?
It becomes smaller.
Why are cations smaller than neutral atoms?
Same protons pull on fewer electrons.
What happens to atomic size when an anion forms?
It becomes larger.
Why are anions larger than neutral atoms?
Increased electron-electron repulsion.
What is the Octet Rule?
Atoms gain, lose, or share electrons to achieve 8 valence electrons.
Which elements are exceptions to the octet rule?
H, He, Li, Be (2); B (6).
Why do atoms bond?
To achieve stability and lower potential energy.
What happens to energy when bonds form?
Energy is released.
What happens to energy when bonds break?
Energy is absorbed.
What determines bond type?
Electronegativity difference (ΔEN).
What defines an ionic bond?
Electron transfer between a metal and a nonmetal.
What ΔEN indicates an ionic bond?
1.7 or greater.
What defines a covalent bond?
Sharing electrons between nonmetals.
What ΔEN indicates a covalent bond?
2.0 or less.
What is a nonpolar covalent bond?
Equal sharing of electrons (ΔEN ≤ 0.4).
What is a polar covalent bond?
Unequal sharing of electrons (0.4 < ΔEN < 1.7).
What defines metallic bonding?
Positive metal ions in a sea of mobile electrons.
Why are metals good conductors?
Their electrons are free to move.
What are ionic compounds commonly called?
Salts.
What are molecular compounds?
Substances formed by covalent bonds.
Why are ionic compounds hard to melt?
Strong electrostatic attractions.
What are intermolecular forces (IMF)?
Attractive forces between molecules.
What are intramolecular forces?
Forces within molecules (chemical bonds).
What is the strongest IMF?
Electrostatic attraction between ions.
What is required for hydrogen bonding?
H bonded to F, O, or N.
What type of molecules exhibit dipole-dipole forces?
Polar covalent molecules.
What is the weakest IMF?
London dispersion forces.
Which molecules exhibit London dispersion forces?
Nonpolar molecules.
What are allotropes?
Different structural forms of the same element.
What are alloys?
Mixtures of metals to improve properties.