Chapter 4 - The periodic table

What is the definition of periodic table

The periodic table is a list of element arranged so that it demonstarte trends in their physical and chemical properties

What is an element?

An element is a substance that cannot be split ino simpler substances by chemical means;

Modern def: An element is a substance made up of only one type of atom

What is a compound?

A compound is formed when 2 or more elements combine chemically

Describe the arrangements of the elements in mendeleevs periodic table

the elements were arranged in order of increasing atomic weight, elemtnts with similar properties were were placed under each other

State mendeleevs periodic law

When elements are arraged in order of increasing atomic weight, the properties of the elements are arranged at regular intervals in other elements

What is the atomic number

The atomic number of an atom is the number of protons in the nucleus of that atom

What is modern periodic table

The modern periodic table is an arrangement of elements in order of increasing atomic number

State the modern periodic table law

When elements are arranged in order of increasing atomic number, the properties of the elements are repeated at regular intervals in other elements

State 3 differences between mendeleevs and the modern periodic table

• mendeleev- elements arranged in order of increasing atomic weight; modern- elements arranged in order of increasing atomic number

• contains gaps for undiscovered elemtnts; contains no gaps

• only has approx 60 elements; has over 100 elements

• transition were not put in a separete block; transition elements are in a separete block

What is an atom

An atom is the smallest part of an element that still has the properties of that element

What is the mass number?

The mass number is the number of protons and neutrons in the nucleous of an atom

What is an ion?

An ion is a charged atom or molecule due to the loss or gain of electrons

What are isotopes?

isotopes are atoms of the same elements which have different mass numbers due to the different numbers of neutrons in the nucleus

Def 2: isotopes are atoms withe same number of protons but different number of neutrons

What is the relative atomic mass?

The relative atomic mass is the average mass of isotopes of an element taking natural abundances into account, relative to one twelfth of the mass of a carbon - 12 atom

Why is the relative atomic mass rarely a whole number?

Relative atomic mass is not a whole number becouse it is the average of atomic masses of all the isotopes

How to calculate the relative atomic mass

(mass number of isotopes * abundances) + (mass number of isotopes * abundances) / 100

State the AUFBAU principle

the AUFBAU principle states that when building up the electronic configuration of an atom in ground state, the electrons occupy the lowest available energy levels

State paulis exclusion principle

paulis exclusion principle states that no more than two electrons may occupy an orbital, and they must have opposite sign

State the hunds rule of maximun multiplicity

the hunds rule of maximun multiplicity states that when two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs