CH 2 Chemicals and Biology

8/3/2019 CH 2 Chemicals and Biology

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CH 2: Chemicals and Biology

ey concepts

oncept 2.1: Matteronsists of elements inure form and combinationalled compounds

lements of Life

ase Study: evolution ofolerance to toxic elements

2.2: element propertiesepend on atoms structure

tomic number and atomicmass

Biology is multidisciplinary scienceEx: use of formic acid by ants to maintain devils garden2.1 matter consists of elements in pure form and combination called compounds2.2 element properties depend on atomic structure2.3 influence of chemical bonding on molecules formation and function2.4 Chemical reactions make and break chemical bonds

All known matter is composed of elements, including organismsElement- substance that cant be broken down any more by chemical reactionsCompound- substance with 2 or more elements in a fixed ration118 elements known, 94 occur naturallyA chemical compound is combination of 2 or more elements held together by chemi

bonds

In a chemical bond, trace elements may not have original properties, but a gain newcharacteristics-Ex: Hydrogen is combustible and a non-fueling element to combustion, Oxygen inon- combustible but a fueling element. Combined make water, non combustible n

fueling

About 20-25% elements are essential to lifeOxygen, carbon, hydrogen, nitrogen (96% of living matter), trace elements Na, K, C

etc.

Very important element is carbon (talk about later on)In biochemistry, trace elements are called micronutrients, trace elements must be take

because organisms cant produce them and are essential to growth, development, e

Some elements can be toxic; arsenicSome species can adapt to harsh chemicals: serpentine communitiesEach element consists of unique atoms- smallest unit of matter that makes up and eleAtoms are composed of subatomic particles

-neutrons ()-protons (+)-electrons (-)

Electron form electron cloud around nucleusElementary particles: Leptons, quarks, hadronsMass

-1.67261027 kg protons

-9.111031 kg electron-1.661027 kg neutron

Atoms vary in different number of subatomic particles-an elements number is the number of protons in its nucleus

Neutron and proton (nucleus) make up atomic mass, measured in Daltons


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otopes

nergy levels of electrons

lectron orbitals

2.3 the formations andunction of moleculesepend on chemicalonding between atoms

ond Types

ovalent bond

There is a flexibility of electrons in the same elementRadioactive decay spontaneously give of particles and energyApplication

-fossil dating-diagnose medical disorder-tracing atom threw metabolic process

Electrons in orbitals determine an atoms chemical propertyIon- atom or group of that lost 1or + electrons, giving a net positive charge (cation),

gained 1 or + electron giving a net negative charge (anion)ion is pretty muchanything that doesnt have a neutral charge

Isotope- atoms with same atomic number but different neutron number(thus differenmass)

Energy is capacity to cause changePotential energy is energy that matter has because of its location or structureHigher energized electrons are back more, an switch of electrons to levels cause spec

lines, color of substance, and creation of ions

Electron shell- electrons state of potential energyPull on outermost electrons from nucleus are weakest and determines elements

valence electron

Elements full of valence electrons are chemically inertOrbital of the 3d space where electrons can be found 90% of the timeEach electron shell consists of specific number of orbitals

s=2p=6d=10f=14

atoms with incomplete valence shells can share or transfer valence electrons with cerother atomsInteractions usually end up staying close, held by attractions-chemical bond

-Covalent bond- sharing of electrons. 2 types:-Nonpolar (similar electro negativities)-Polar (dis-similar electro negativities)

-Ionic bond

-Weak chemical bonds- Hydrogen bonds & Van der Walls interactions

Covalent bond- share an electron (nonpolar vs poIn cov. Bond, shared electron count as part of ea

atoms valence shell

A molecule consists of 2 or more atoms held togby covalent bonds

In single cov bond, or single bond, is sharing of pair of valence electrons

In double cov bond, or double bond, is shareing two pairs of valence electrons

Cov. Bond can form between same element of


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onding details

lectronegativity and bondolarity

onic bond

Weak bond

W. bond- Hydrogen Bond

W. bond- Van der Waalsnteraction

Molecular shape and

unction

: 2.4 Chemical reactionmake and break bonds

ou should now be able to

different

Bonding capacity is called the atoms valenceAtoms in a molecule attract electrons to varying degrees based on the atoms

electronegativity-the more electronegative an atom, the stronger the attractions of shared electron to

In nonpolar cov bond, the atoms share the electron equallyIn polar cov bond, one atom is more electronegative, and atoms do not share electro

equally

Unequal sharing of electron caused partial - or + charge for each atom or moleculeAtoms sometimes strip electron from their bonding partner

-Ex: transfer of an electron from sodium to chlorine-after transfer on an electron, both atoms have charges called ions

Ionic compounds are called saltsSalts hydrolyze to produce hydroxide ions (basic) or hydronium ions (acid) when

dissolved in water

Strongest bond in organisms are covalent bonds that form in cells moleculesWeaker chemical bond (ionic and hydrogen bonds) reinforce shapes of large molecu

and help molecules adhere to each other

Hydrogen bond forms when hydrogen atom covalently bonded to one electronegatiatom is also attracted to another electronegative atom

Temporary dipoles created when electrons are lopsidedWhen electrons move randomly, sometimes they get closer to each other, the uneven

concentration causes one side to be negatively charged than the other. Explains honon-polar molecules can have attractive forces.

Molecules shape is very important to its function, usually.Shape determined by-position of valence orbitals

-hybridization between s and p orbitals to create specific molecular shapes

Biological molecules recognize & interact with a specifity based on molecular shapeMolecules with similar shape can have similar biological effectSimilar enough to work (endorphin and morphine)Chemical reaction are making and breaking chemical bondsThe starting molecules are called reactants, final molecule is called productsPhotosynthesis: sunlight power to convert carbon dioxide and water to glucose and

oxygen

Some chemical reactions go to completion: all reactants are converted to productsAll chemical are reversibleChemical equilibrium is reached when forward and reverse reaction are equal1 identify four major elements2 distinguish between the following pairs: neurons and protons, atomic number and mnumber, atomic weight and mass number3 Distinguish between and discuss the biological importance of the following nonpolcovalent bonds, polar covalent bonds, ionic bonds, hydrogen bonds, and van der Waainteractions


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CH 2 Chemicals and Biology