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Atomic Structure

Atomic Structure. S1-2-04 Explain the atomic structure in terms of subatomic particles and define atomic number and atomic mass. S1-2-05 Assemble or draw Bohr atomic models. Vocabulary & People orbit valence Amu (µ) atomic mass atomic number Bohr. 5. Bohr (1913 ).

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Atomic Structure

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  1. Atomic Structure

  2. S1-2-04 Explain the atomic structure in terms of subatomic particles and define atomic number and atomic mass. S1-2-05Assemble or draw Bohr atomic models. Vocabulary & People orbit valence Amu (µ)atomic mass atomic number Bohr

  3. 5. Bohr (1913) “Flame Test” experimentsshowheatedelements emit a unique pattern of colour. This unique colour signature can be used to identify elements in mixtures or compounds • Emitted light was from excited electrons

  4. Hypothesis: Electrons move in organized circular paths of different distances around a nucleus. Orbit: location of electron motion around a nucleus. Only a specific number of electronsfill each orbit Bohr reasoned that random electron movement cannot produce the same unique colour pattern EVERY TIME

  5. Bohr’s model is called the “planetary” model 1st– holds two electrons (e-) 2nd– holds eight e- 3rd – holds eight e- • Electrons occupy the closest orbital first • Elements have a different number of electrons

  6. Valence: • Last (outer) atom orbit • All electrons in last orbit - valence electrons The number of valence electrons an atom has determines how the atom chemically reacts

  7. Hydrogen has a total of 1 e- (1 valence e- ) Boron has a total of 5 e- (3 valence e- ) Neon has a total of 10 e- (8 valence e- )

  8. Atoms Neutron(no) –nucleus particle with no charge. Proton(p+)–nucleus particle with (+) charge. Electrons(e-) –particles in orbits with a (-) charge. • Protons have a mass of 1 Atomic Mass Unit (μ) • Neutrons are the same size - also 1 μ • Electrons are considered zero mass Amu is just a unit to measure verysmallmasses equal to 1.6605 x 10-24 grams + Protons Neutrons - electrons

  9. The information on the Periodic Table will help us build atomic models – “Bohr” models

  10. Atomic mass • Larger value – total mass in Amu • Equals the number of p+ and no in the nucleus • Round off the value Since protons and neutrons each weight 1 amu –there must be 4 protonsandneutronsin the nucleus of a helium atom to weigh a total of 4 amu

  11. Important points: • No TWO elements have the same number of protons. • The number of protons in an element does NOT change. Atoms can lose and gain neutrons and electrons – since protons have NEVER been shown to change we use this to identify elements

  12. Atomic number • Smaller value – no units • Equals number of protons • p+number is used to identify an element Since atoms are neutral (equal number of protons and electrons) – you can use Atomic number to find the number of protons OR electronsin the atom

  13. Sulfur (S) How many protons are there in one atom of Sulfur? Atomic number 16 - 16 p+ How many electrons in one atom of Sulfur? Atoms are neutral - 16 e- How many neutrons in one atom of Sulfur? Atomic mass 32 32-16 = 16 no How many protons in 3 atoms of Sulfur? 3 x 16 = 48 p+

  14. An atom is found with 19 protons: What element is this? Potassium How many electrons in one atom of Potassium? Atoms are neutral – 19 e - How many neutrons in one atom of Potassium? At mass – At number 39 – 19 = 20 no How many protons in 10 atoms of Potassium? 10 x 19 p + = 190 p +

  15. Drawing a Complete Bohr Atom: • Determine the number of no, p+, e- in the atom. • Draw the nucleus. • Label the #of protons and neutrons. • Add orbits and fill with the appropriate # of e-. Nitrogen (N) p+ : 7 no : 14 – 7 = 7 e- : 7 7p+ 7no

  16. Sodium (Na) p+ : 11 no : 23 – 11 = 12 e- : 11 11p+ 12no

  17. CAN YOU ANSWER THESE QUESTIONS? S1-2-04 How do you use atomic mass and atomic number to identify parts of the atom? S1-2-05 How do you draw an atom using the Bohr model? Vocabulary & People orbit valence Amu (µ)atomic mass atomic number Bohr

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