Biology 1020

How do you determine valence electrons?

nuaru 13. 2011

2

Atoms and Molecules

Valence Electrons

outer must electrons

· Valence numbero how many bonds can an atom

form?

valence #

1

4

2

bonds - need at least atoms

cavaleut catons share electrons

How do you identify an ionic bond?

-'non polar covalent - they share - Hydungun (He er'H-H)

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equally

Sume charge on buta

. polak covalent band - atoms shure e unequally

What is carbon dating and how does it work?

Don't forget about the age old question of What does linguistics study?

Hal it H-41 3L

Shared é spends mare

time around Cl

7 82

local charges

Cl is niare electronegutive

- Ionic bond - leleutrostatic) formsketyrees ions, no Sharing Don't forget about the age old question of What is the role of gravity as a prime mover?

•jon - a charged atene 'cation - positively charged wton 'anics - bregutively charged atom If you want to learn more check out How does exhaustion lead to death?

Na.

.:

Na ll protons

17 protons -toe

toe

Cation

anion

Biology 1921

January 13,2014

1 Chapter 3 Atoms and Molecules_peyz If you want to learn more check out What do correlations show?

#Neutrons

wat radioactive

Alot radioactive

radioactive

TH pratium leurysky) iH Deatekivans PH tritium 12 C Carbon - 12 13 C Carbon 13 it C Carbon-14 We also discuss several other topics like What economics is all about?

以七ubu

Stable

Stable

+

Earbon Dating

g

r adioactive * hallo life-suse years

Carbon-Dating ___6.12;6. 14 constant ratio in atmosphere in living organisms Don't forget about the age old question of What does developmental psychology study?

- Plants get it from Coz

Animals - get it from food (releases Cos)

· Death no more carbon enters

.6.14 decay

6-12 - does not deny

Se ratie changes Tracers - detected a

“diagnose diseases Electrons 6-) - to weight

determine reactivity of an atom orbit the nucleus!

· "Shells"

- Shell / - ze

Shell 2 5 8é - Shell 3 = be

-

- shell must always

fall in order 1,2,3

like to be mis pairs e differ is energy level - mare e from Shell I to shell 2 = must add energy

mave e train shell 2 to shell l = energy must be released

orbitals - position of en

Larbital halds max af de

#urbitals I

Shell

I Shell a

I Biolog

1020

January 13, 2016

| Chapter 2 - Atoms and Molecules

per

dy Sour

Elements - 92 naturally occurring - rest are made in Jab

· Pure ferm - cannot be broken down Helm N - most important for living things larkpo present is small amounts (trace elements)

Molecules / compounds - atoms BOND

Properties

-- Nalsodium) -pure-forme - explosive

-Cl lablarine)-poison gas

- NaCl - table salt Trace elements

- small amount ex ijodine Atom - smallest unitat element

- subatomia particles

Protons (+)-in nucleus

-lamu (dacten) Electrons (-) - nat ins nucleus -orbit

alltoo small to measure)

Neutrons - neutral -in nucleus - - lamu

etra

Atoms

I Atomic number = # of protons in an atom

it pratium leveryday) 2. In a neutral atom - # pratens = #clectrons 3. Atomic weight (muss)

La #prótons + # neutrons

He -2 pretons - @electronic2 neutrons Co Na -12 neutrons - 11 protons - Helectrons 4._ Isotopes - different stoms_sf the sumse element

a. # of neutron's varies (wary atomic weight) k stable or unstable (radioactive) !

Radioactive - undergo 'olecay" limit radiation) d. "half-life" - time requires for bult of the atoms in the sample to

allary