Atomic Structure and the Periodic Table

Simple model of atom

Atoms, elements and compounds

COMPOUNDS- TWO OR MORE ELEMENTS CHEMICALLY BONDED TOGETHER. CAN ONLY BE SSEPERATED BY CHEMICAL REACTIONS.

ATOMS MAKE UP ELEMENT.

Mixture

MIXTURE- TWO OR MORE ELEMENTS NOT CHEMICALLY BONDED TOGETHER.

CAN BE SEPERATED BY: FILTRATION, CRYSTALLISATION, SIMPLE DISTILLATION, FRACTIONAL DISTILLATION AND CHROMOTOGRAPHY.

Development of the model of the atom

  • FIRST: ATOMS THOUGHT TO BE TINY SPHERES THAT COULD NOT BE DIVIDED

  • DISCOVERY OF THE ELECTRON WHICH LED TO THE PLUM PUDDING MODEL (ATOMS THOUGHT TO BE A POSITIVE CHARGED BALL WITH NEGATIVE ELECTRONS EMBEDDED IN IT)

  • ALPHA PARTICLE SCATTERING EXPERIMENT: CONCULSION WAS THAT THE MASS OF THE ATOM WAS CONCENTRATED AT THE CENTRE (NUCLEUS)

    • POSITIVELY CHARGED ALPHA PARTICLES BEING REPELLED AND DEFLECTED BY A SMALL CONCENTRATION OF POSITIVE MASS.

  • NEIL BOHR: SUGGESTED THAT THE ELECTRONS ORBIT THE NUCLEUS AT FIXED DISTANCES.

  • JAMES CHADWICK WORK’S: DISCOVERED THE NEUTRON.

Mass and Size of atoms

PARTICLE

RELATIVE CHARGE

PROTON

POSITIVE (+)

NEUTRON

NEUTRAL

ELECTRON

NEGATIVE (-)

PARTICLE

RELATIVE MASS

PROTON

1

NEUTRON

1

ELECTRON

VERY SMALL

MASS NUMBER: SUM OF PROTONS AND NEUTRONS

ATOMIC NUMBER: NUMBER OF PROTONS

ISOTOPES: SAME ELEMENT WITH DIFFERENT NUMBER OF NEUTRONS

The Periodic table

  • ELEMENTS ARE ARRANGED IN ORDER OF ATOMIC NUMBER AND SO ELEMENTS WITH SIMILAR PROPERTIES ARE IN COLUMNS

  • ELEMENTS IN THE SAME GROUP HAVE THE SAME NUMBER OF ELECTRONS IN THE OUTER SHELLS

The Early periodic table

  • JOHN NEWLANDS: ORDERED HIS TABLE IN ATOMIC WEIGHT

  • DMITRI MENDELEEV: LEFT GAPS FOR ELEMENTS THAT HADN’T BEEN DISCOVERED

The Modern periodic table

  • KNOWLEDGE OF ISOTOPES

  • ELECTRONS, PROTONS, AND NEUTRONS WERE DISOCVERED IN THE EARLY 20TH CENTURY

Metals and Non-Metals

METALS= ELEMENTS TGAT REACT TO FORM + IONS