Periodic Table Unit Flashcards
What happens to ionization energy as it goes across a period?
It increases.
Who was the first to publish the periodic table of elements?
Dmitri Mendeleev
How did he group the elements?
In columns by similar properties in order of increasing mass.
How is the modern periodic table organized?
In the modern periodic table, elements are arranged in order of increasing atomic number. elements with similar properties are in the same column.
What determines the chemical properties of an element?
The number of valence electrons.
What are electron dot diagrams?
Uses the symbol of the element and dots to represent the electrons in the outer energy level.
What are the characteristics of metals?
They are lustrous (shiny) solids, generally high melting points and densities, malleable (can be shaped), ductile (can be pulled into wires), conductors of heat and electricity, and they lose electrons.
what are the characteristics of nonmetals?
They are poor conductors of heat and electricity, often dull and brittle, insulators, and gains electrons.
How does distance affect the affinity for electrons?
The shorter the distance between the nucleus and the valence electrons, the more strongly they are held by the atom.
What is the relationships between number of electrons and the force holding it?
The more electrons between the nucleus and a valence electron, the weaker the force holding it.
What is ionization energy?
The energy required to remove an electron from an atom. The greater the attraction the greater the ionization energy, the stronger the attraction between the nucleus and the valence electrons, the harder it is to remove electrons.
What are non-metals’ ionization energy/chemical properties?
- They have a strong attraction between nucleus and valence electrons (high ionization energy) difficult to remove electrons
- They have high electronegativity
What are metals’ ionization energy/chemical properties?
- They have low ionization energy
- They lose electrons when bonding (metal atoms nuclei have a weak attraction for their valence electrons and so lose them)
- Alkali and alkaline earth metals have little valence electrons so they are the most reactive of the metals
- Metals are found combined in nature
What happens to atomic radius as it goes down a group?
It increases.
What happens to atomic radius as it goes across a period?
It decreases.
What happens to electronegativity as it goes down a group?
It decreases.
What happens to electronegativity as it goes across a period?
It increases.
What happens to ionization energy as it goes down a group?
It decreases.
What is atomic radius?
The distance from the nucleus to the outermost electron.
What is electronegativity?
A measure of the tendency of an atom to attract a bonding pair of electrons.
Why does atomic radius decrease across a period?
There are a number of protons in the nucleus so the nucleus more strongly attracts its orbital electrons and pulls them closer to it, while electron shielding remains similar.
Why does atomic radius increase across a group?
Increasing number of energy levels.
Why does electronegativity decrease down a group?
As you move down a group, the radius increases as more electrons shells are added. Since the outer electrons (those involved in bonding) are farther from the nucleus, they will feel the “pull” of the nucleus less. Larger atoms have lower electronegativity.
Why does electronegativity increase across a period?
As we move across the period, the effective nuclear charge increases and the atomic size decreases.
