Periodic Table Flashcards
How is the periodic table arranged?
Elements are arranged in order of increasing atomic numbers. They are organized into horizontal rows known as periods and vertical columns known as groups
What are metalloids?
They are elements found along the diagonal line in the periodic table which exhibit both metallic and non-metallic properties
Trend of metallic character of elements?
The metallic character of elements decreases from left to right across a period
Electron shells
Elements with the same number of electron shells belong to the same period
Trend of metallic character down a group + reason
Metallic character increase down a group due to increase in size of the atoms. Valence electrons are further away from the nucleus and are not as strongly attracted.
Larger atoms lose their electrons more readily than smaller atoms, hence metallic character increases down a group
Physical properties of group 1 metals (aka alkali metals)
Soft and easily cut with a knife
Relatively low melting and boiling points
Densities are relatively low and first 3 elements have lower density than water, enabling them to float
Chemical properties of alkali metals
They are highly reactive and react easily with oxygen and water
Trend of physical properties as atomic size increases down alkali metal group
Melting and boiling points decrease while density increases
Reactivity of metals also increases as we move down the group. Increase in atomic size means valence electrons are further away form the nucleus and are more easily lost
Reaction of alkali metal with water
Forms an alkali and hydrogen gas
Alkali metals reactions with other non-metals
Alkali metals react with other non-metals to form ionic salts which are soluble in water
Why are alkali metals string reducing agents?
They easily give away their valence electrons
Properties of halogens
Found as diatomic molecules
Low melting and boiling points
They are coloured substances
Trend of physical characteristics of halogens moving down the group
Melting and boiling points increase
Colour intensity increases
Why are halogens highly reactive?
They only need to gain one electron for noble gas configuration
Trend of reactivity of halogens down a group
Reactivity decreases as we move down the group
As atoms increase in size, the force of attraction between valence she’ll electrons and nucleus is weaker. As a result, larger halogens do not gain electrons as readily as smaller ones
