Warm UpWarm Up 9-28-159-28-151.1. What are valence electrons?What are valence electrons?

2.2. How many valence electrons do elements How many valence electrons do elements in the alkali and halogen group have?in the alkali and halogen group have?

3.3. Which of these elements are metal?Which of these elements are metal?Al, As, Cl, LiAl, As, Cl, Li

4.4. What are the charges of the subatomic What are the charges of the subatomic particles?particles?

HomeworkQuiz next class Unit 3Finish review WS

Agenda-Notes Unit 3-3-Lab Conservation of mass-WS Unit 3 Quiz Review

SEAP SEAP - Science & Engineering - Science & Engineering Apprenticeship ProgramApprenticeship Program

Deadline to apply Oct. 23Deadline to apply Oct. 23 Must be 16 or older during the summerMust be 16 or older during the summer Spend 8 weeks during the summer doing

research at the Naval Surface Warfare Center - (behind Norco College)

$3,300 stipend for the 8 weeks https://seap.asee.org/https://seap.asee.org/

SEAP SEAP - Science & Engineering - Science & Engineering Apprenticeship ProgramApprenticeship Program

Applicant has to write 4 statements including: Career goals: describe your career goals and in which

way this program would help you fulfill those goals. Academic interests: describe any special interest you

may have that would make you a valuable participant. Describe any awards or honors you have received.

Research experience: describe any research experience you may have in relation to this program.

Technical skills: describe any technical skills you may have, related to the science and engineering disciplines.

Unit 3-3Unit 3-3Periodic TrendsPeriodic Trends

Atomic radiusAtomic radius Ionization energyIonization energy ElectronegativityElectronegativity Electron affinityElectron affinity

Periodic TrendsPeriodic Trends Atomic RadiusAtomic Radius: : The estimated distance The estimated distance

from the nucleus to the outer most from the nucleus to the outer most electronselectrons

IncreasesIncreases down a groupdown a group As electrons energy levels are added, the As electrons energy levels are added, the

atom becomes largeratom becomes larger DecreasesDecreases across a period across a period # protons increases which pulled the v.e. # protons increases which pulled the v.e.

closer to the nucleus closer to the nucleus

Atomic Radius TrendAtomic Radius Trend

Radius decreases

Rad

ius In

creases

Rad

ius

dec

reas

es

Periodic TrendsPeriodic Trends

Ionization Energy Ionization Energy - - The energy The energy required to required to remove one electron from an atom or ionremove one electron from an atom or ion DecreasesDecreases down a group down a group Electrons are farther from the nucleus and Electrons are farther from the nucleus and

easier to removeeasier to remove IncreasesIncreases across a period across a period

Periodic TrendsPeriodic Trends

Electron Affinity - Electron Affinity - the energy change that the energy change that occurs when an electron is added to a occurs when an electron is added to a neutral atomneutral atom Decreases Decreases down a group down a group Increases Increases across a periodacross a period

Periodic TrendsPeriodic Trends

ElectronegativityElectronegativity - - the ability the ability of an atom of an atom to attract electrons to itselfto attract electrons to itself Decreases Decreases down a groupdown a group Increases Increases across a periodacross a period

Check InCheck In

Consider the following elements: Ca, Fe, Ga, Br

Largest radius? Smallest radius? Highest electronegativity? Lowest ionization energy level?

Trends SummarizeTrends Summarize

Conservation of MassConservation of Mass PurposePurpose: Find a method to test the law of : Find a method to test the law of

conservation of massconservation of mass MaterialsMaterials: :

electronic electronic scale 1 balloon

125 mL flask 5 g baking soda

50ml graduated cylinder 15 mL vinegar

1) Weight of baking soda = _______g

2) Weight of compounds and reaction vessel before reaction occurs = ________g3) Weight of compounds and reaction vessel after they reacted = _________g

AssignmentsAssignments

Notes SummaryNotes Summary Unit 3 Quiz review worksheet Unit 3 Quiz review worksheet

due next class due next class (answers posted tonight after 7PM on my (answers posted tonight after 7PM on my website)website)