The Periodic Table (General) Flashcards
What is the periodic table?
The Periodic Table is a tabular arrangement of elements in order of increasing atomic number (number of protons)
Each element in the same period..
…differs from the preceding element by addition of an electron to the electron shell and a proton to the nucleus, and possess progressively different physical and chemical properties.
Elements in the same group…
…have the same number of valence electrons and possess related chemical and physical properties.
What is periodicity?
The occurrence of similar properties at regular intervals with increasing atomic number on the Periodic Table
State the Periodic Law
Properties of elements are a periodic function of their atomic numbers
Periodic Properties
Atomic Radius Ionic Radius Ionization Energy Electronegativity Electron Affinity Metallic Character Melting and Boiling Points
Atomic Radius
Half the distance between 2 nuclei of a homo-nuclear diatomic molecule or adjacent atoms
Atomic Radius trend
Increases down the group
Decreases across a period
What are the reasons for the trends in atomic radius?
As you go across a period, the radius gets smaller because electrons are in same energy level. Also, increase in proton number means more nuclear charge.
Outermost electrons are closer to the nucleus because more protons are pulling them in the same direction, whereas the electrons are scattered.
As we go down a group, each atom has another energy level so the atoms get bigger.
What are the factors affecting atomic radii trends?
- Energy Level - A higher energy level is further away.
- Charge on nucleus - More protons means higher charge which pulls electrons in closer.
- Shielding effect - electron repulsion
Explain the sizes of ions
Positive ions give out electrons and are smaller. Negative ions receive electrons and are bigger.
Which is larger? Atomic or ionic radii?
Atomic radii
What causes changes in elements as we move across the period?
Increase in nuclear charge. It makes ionization harder and the tendency to attract electrons easy.
What is Ionization Energy?
Ionization energy is the minimum energy (kJ/mol) required to remove an electron from a gaseous atom in its ground state.
Why is Ionization Energy referred to as endothermic?
Ionization energy is always endothermic, that is energy is added to the atom to remove the electron.
Is ionization energy endothermic or exothermic?
Endothermic
Explain the relationship between Ionization Energy and Atomic Radius?
Ionization energy and atomic radius are inversely proportional. The larger the atom is, the easier it is to remove its electrons. The energy required to remove an electron from an atom reduces as the size of the atom increases because electrons are easier to steal.
What are the factors that affect ionization energy?
RSNS (ReaSoNS)
Radius - The higher the radius, the smaller the IE
Sub-level - An electron from a full or half-full sub-level requires additional energy to be removed.
Nuclear Charge - The higher the NC, the greater the IE
Shielding Effect - The greater the shielding effect, the smaller the IE required.
What is the periodic trend for IE?
The first IE decreases down the group because the atomic radius of the atoms increases and there is more shielding.
Across the period, IE generally increases from left to right.
Where do we have an exception for IE trends?
Across the period, for full and half-filled orbitals
What is electronegativity?
Electronegativity is a measure of the ability of an atom in a molecule to attract electrons to itself.
What is the electronegativity trend on the Periodic Table?
Electronegativity decreases as you go down the periodic table and increases from left to right across a period.
What makes Period 3 unique?
Structure and bonding Elements change from metal through metalloid to non-metals. Acid-base properties Redox properties Solubility and complexing properties
How many types of oxides can elements can form and what influences the type?
Three; The oxidation number of Oxygen
What are the types of oxides elements can form?
Normal oxide - oxidation state of –2
Peroxide- oxidation state –1
Super oxide = oxidation state -½
What are the elements in Period 3 of the Periodic Table?
Na, Mg, Al, Si, P, S, Cl, Ar
Which elements of the Periodic Table are in a diagonal relationship?
Li and Mg, Be and Al, B and Si
Lithium and Magnesium
Carbonates - Both are insoluble and decompose on heating. G1 carbonates are generally soluble and don’t decompose on heating
Oxides - Both oxides are hydrated
Chlorides - Both only give simple oxides
Hydration - Both Li+ and Mg2+ are heavily hydrated in solution.
Be and Al
Nitric Acid - Both are passive and won’t dissolve
Alkali - Both dissolve, giving hydrogen
Acidity/Alkalinity - Both are amphoteric
Oxides - BeO and Al2O3 are amphoteric
Chlorides - Both BeCl2 and AlCl3 are electron deficient and act as Lewis acids
B and Si
Oxides - Both are weakly acidic
Hydrides - Both give unstable hydrides, the boranes and silicanes
Chlorides - Both BCl3 and SiCl4 are volatile and will undergo hydrolysis to give acidic solutions
What are the elements in G1?
Li, Na, K, Rb, Cs, Fr
Is Hydrogen a G1 element? Why?
No. It is there because it can lose an electron to become a hydrogen ion like the rest. It can also gain one like the halogens to form the hydride ion.
What groups of the Periodic Table can hydrogen stay?
1 and 7
What are the general characteristics of G1 elements?
- Very reactive, pure form impossible but extracted by electrolysis
- Melting and boiling points decrease down the group
- All metals
- Good reducing agents
- Highly electropositive
What is the only stable nitride of G1?
Lithium nitride (Li3N)
Why isn’t Li a typical G1 element?
It’s small size and large charge.
What is so special about G1 carbonates and heat?
They don’t decompose easily on heating.
