Periodicity Flashcards
The group number is the same as?
The number of valence electrons in an atom.
The period number gives the?
Number of occupied energy levels.
What is the nuclear charge?
It is the same as the atomic number of an element.
How is the effective nuclear charge of an atom explained?
The effective nuclear charge is ‘experienced’ by the outer electrons. It is less than the nuclear charge because the valence electrons are shielded from the nucleus and repelled by the inner electrons.
Describe the trends of atomic radii.
Increase DOWN a group, decrease ACROSS the period.
Describe the trends of ionic radii.
- Positive ions are smaller than their parent atoms
- Negative ions are larger than their parent atoms
- Decrease of elements between group 1 and group 4 for POSITIVE ions.
- Increase of elements between group 4 and group 7 for NEGATIVE ions.
- Increase DOWN a group.
Describe trends of first ionization energies.
Increase across a period; decrease down a group. Reverse of atomic radii.
What is electronegativity of an element?
the measure of the ability of its atoms to attract electrons in a COVALENT BOND.
Describe the trends of electronegativity.
Increases from left to right across a period; decreases down a group
What is the most electronegative element? What is the least electronegative element?
Fluorine - also the most reactive as a result.
Caesium - least reactive as a result.
Describe the trends of melting points.
They decrease down group 1, increase down group 7. General increase across a period and reach a max at group 4.
Describe elements of group 1-3 vs elements of groups 5-7.
Group 1-3: tend to lose electrons to find stability, are generally metals.
Groups 5-7: tend to gain electrons to find stability, are generally non-metals.
The alkali metals react with water to produce?
Hydrogen and a metal hydroxide.
The alkali metals and halogens react to produce?
Ionic halides.
Halogens and silver make?
Insoluble salt. So if you have an unknown halide just mix it with silver and bam.
