Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/30

Click to flip

30 Cards in this Set

  • Front
  • Back

ESSENTIAL ELEMENTS

●organism needs to live & reproduce

What 4 elements make up 96% of living matter?

Carbon,Hydrogen,Oxygen,Nitrogen

Trace elements

●elements needed by organisms in tiny amounts

Subatomic particles

●atoms are composed of these


●NEUTRONS, PROTONS, & ELECTRONS

Atomic nucleus

●protons + neutrons packed together in this dense core

What do electrons form around an atomic nucleus?

A cloud of negative charge

Dalton

Unit of measurement


●same as AMU (Atomic Mass Unit)


●NEUTRONS & PROTONS AROUND 1 DALTON.

Atomic number

●# of protons in nucleus


●written as a subscript to the left of tglhe element symbol

Mass number

●sum of protons & neutrons


●written as a subscript in the upper left of the element symbol

Atomic mass

●total mass of an atom

WHEN AN ATOM HAS MORE NEUTRONS THAN OTHER FORMS OF THAT ELEMENT, IT IS CALLED...

AN ISOTOPE

If an atom of helium were the size of a football stadium, the NUCLEUS would be the size of...

A pencil eraser

Where are the 3 electron shells located in relation to the nucleus?

1st- closest to nucleus


2nd- middle to nucleus


3rd- farthest from nucleus

How many electrons can the 1st shell of an atom hold?

ONLY 2

HOW MANY ELECTRONS CAN EACH SHELL >1 HOLD?

8

Covalent bond

●sharing of a pair of electrons of valence electrons by 2 atoms

What is an atom's valence?

● # of covalent bonds an atom can form


● usually = # of unpaired electrons in its valence shell

Electronegativity

●attraction of an atom for the electrons of a covalent bond

THE MORE ELECTRONEGATIVE AN ATOM IS, THE MORE STRONGLY IT PULLS SHARED ELECTRONS TOWARDS _________.

Itself

NONPOLAR COVALENT BOND

Electrons are shared EQUALLY between 2 atoms of similar electronegativity


●ex: H2, O2

POLAR COVALENT BOND

When an atom is bonded to a more electronegative atom


ELECTRONS NOT SHARED EQUALLY


ex: H2O. Oxygen = super electronegative... electrons spend more time near the oxygen

IONIC BOND

Chemical bond resulting from the attraction between oppositely charged ions

Hydrogen bond

●weak chemical bond


●slightly pos H atom in a molecule is attracted to slightly neg atom in another molecule or in another region of the same molecule

COHESION

Linking together of like molecules


Usually by hydrogen bonds

Adhesion

Clinging of one substance to another


Ex:water to plant cell walls

Specific heat

Amount of heat that needs to be absorbed/lost to change 1g of a substance 1°C

HYDRATION SHELL

Sphere of water molecules around each dissolved ion

BUFFER

Substance that minimalizes changes in the concentrations of h+ and oh- in a solution

An atom's valence

# of covalent bonds it can form

Enzymes

Specialized macromolecules (usually proteins)


Speed up chemical reactions