Atomic Structure And The Periodic Table

Atomic Structure And The Periodic Table

• 
• Pie de imagen: Atomic structure
• Element= A substance which contains only one type of atom.
• Atomic Number= The number of protons in the nucleus.
• Mass Number= Total number of protons and neutrons. It can be calculated by subtracting the atomic number from the mass number.
• i.e. mass number- atomic number= neutrons.
• number of protons = number of electrons
• mass number= protons + neutrons
• neutrons= mass number - number of protons
• e.g. cobalt
• 59- Mass number
• CO -Symbol for element
• 27 -Atomic number

Charges: Protons, Neutrons And Electrons

• 
• Pie de imagen: Charges for protons, neutrons and electrons

Isotopes and Electronic structure

• Isotopes: Atoms that have the same number of protons but different number of neutrons.
• Atoms are more stable (less reactive) if they have a full outer shell of electrons.
• Only atoms in group 8 e.g. helium and neon have full outer shells of electrons.
• Atoms in group 1 to 7 do not have a full outer shell of electrons so they want to fill their outer shell.
• From group 1 to 3 the shells lose electrons.
• In Group 4 they tend to share electrons, so you could say that they both lose or gain
• Group 5 to 7 the shells gain electrons.
• Working out an element's electronic structure:
• 1) Find the element in the periodic table.
• Work out which period it is in, and draw that number of circles around the nucleus.
• 2) Work out which group the element is in and draw that number of electrons in the outer circle.
• With 8 for Group 0 elements- except helium.
• 3) Fill the other circles with electrons.
• Remember: 2 in the first 8 in the second and third and 18 in the fourth.
• 4) Finally count your electrons and check that they are equal to the atomic number.