Atomic Structure Science 10

Atom Models  Models have changed and become more detailed over time  Each model has allowed for new hypotheses to be made and predictions to be tested

Parts of an Atom  Atoms are made up of subatomic particles  Protons (p+)  Neutrons (n)  Electrons (e-)  The atoms for each element have a different number of subatomic particles  Atoms are neutral  They have no charge

Inside the Atom

Relative Size in an Atom

Atomic Number  Atoms from different elements have different number of protons (p+)  Atomic number = number of protons  Because atoms are neutral  Number of protons=number of electrons (e-)

Mass Number  Mass number = protons (p+) + neutrons (n)  To solve for number of neutrons  Neutrons = mass number - protons Atomic number = 2 Mass number = 4 Number of protons = Number of electrons = Number of neutrons = Helium Atom

Mass Number  Mass number = protons (p+) + neutrons (n)  To solve for number of neutrons  Neutrons = mass number - protons Atomic number = 2 Mass number = 4 Number of protons = 2 Number of electrons = 2 Number of neutrons = 2 Helium Atom

Isotopes  Isotope – atoms of the same element that have different number of neutrons  Have the same atomic number  Have different mass number  Different number of neutrons

Isotopes  Have the same chemical properties  How they react  This is based on their valence electrons  Have different physical properties  Appearance, density, diffusion behaviour Common Isotopes 3 Isotopes of Hydrogen: 1 H 1 2 H 1 3 H 1 2 Isotopes of Carbon: 12 C 6 14 C 6 2 Isotopes of Chlorine: 35 Cl Cl 17

Electron Configuration  The number of electrons that each energy level (orbital, shell) can hold  Atoms have 7 energy levels which each have a maximum number of electrons  Level 1 – Holds 2 electrons  Level 2 – Holds 8 electrons  Level 3 – Holds 8 electrons  Electrons always fill the first energy level before filling the second, etc.

Electron Configuration

 Electron configurations are written with the number of electrons in each energy level followed by a comma  Sodium: 23 Na 11 has 11 electrons: 2, 8, 1  Beryllium: 9 Na 4 has 4 electrons: 2, 2 12 C 6 SiHe PNe 12 C 6 FAlO Fill in the following table by using your periodic table

Understanding Checkpoint  Read and hi-light textbook pg.  Read handout on radioisotopes  Worksheets  Quiz in 2 classes

Next Up  Quiz  Ions  Valence electrons  Video  Periodic Table Lesson