The periodic table of elements Flashcards
what is the periodic law
“properties of elements are periodic functions of their atomic number”
- when elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties
What are the characteristics of group 1 alkali metals
- silver coloured, soft metals
- highly reactive and rarely found in elemental form in nature
What are the characteristics of group 2 alkaline earth metals
- silver coloured, soft metals
- reactivity similar to alkali metals
What are the characteristics of group 8 noble gases
- chemically inert
- nonmetallic
- atomic gases at standard conditions
What are the characteristics of group 7 halogens
- highly reactive and toxic
- nonmetallic
states change down the group
What are the characteristics of metalloids
- properties of both metals and nonmetals
What are transition metals
- elements with at least one oxidation state that has a partially filled d-subshell
- metals with high densities, melting and boiling points
- form coloured compounds and complex ions
- valencies are variable and ions readily undergo oxidation or reduction
What are the characteristics of lanthanides
- in the f-block
- also known as rare earth metals
- shiny and silvery-white, stain easily when exposed to air
- have high melting and boiling points
What are the characteristics of actinides
- in f-block
- all radioactive
- very dense metals with distinctive structures
- numerous allotropes e.g. plutonium has at least 6 allotropes
what is the general pattern of “size of atoms”
increases on descending a group
what is the general pattern of “metallic character”
increases descending a group
what is the general pattern of “reactivity”
- metals become more reactive on descending a group
- nonmetals become less reactive
generally what does the valency of groups 1, 2, 3, 4 equal
group number
generally what does the valency of groups 5, 6, 7, 8 equal
8 - group number
what is valency
the number of chemical bonds formed by an atom
how can valency be obtained
from its position in the periodic table or its electronic structure
the valency of an atom is equal to its charge
- however, some elements can have multiple valencies
e.g - phosphorus and nitrogen = 3/5
- transition metals
- heavier elements e.g. Pb = 2/4
what is molecular formula
the exact number of each type of atom present in one molecule of the compound
what is empirical formula
elemental composition of a compound expressed as a ratio
how do you work out empirical formula
% mass / Ar divided by the smallest number
how to calculate percentage mass
- calculate molecular mass of compound
- then obtain Mr of element to be calculated (X)
- X x 100/total molecular mass
