chap 2.1-2.4 bio

Matter

Refers to anything that has mass and takes space. It exists in four states solid, liquid, gas or plasma

All matter ( living & nonliving )

Is composed of basic substances called elements

Element

Is a substance that cannot be broken down into another substance with different properties (composed of one type of atom)

What six elements make an organism

Carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur

Atom

Smallest part of an element that displays the property of the element

Protons

Positive charge

Neutrons

No charge ( orbiting around the nucleus electron shells )

Electrons

Negative charge, low mass

Each element is?

Represented by one or two letters to give it a unique atomic symbol

Atomic number

Is equal to the number of protons in each atom of an element

Mass numbers

Is equal to the sum of the number of protons and neutrons in the nucleus

Atomic mass

Is equal to the average mass of all isotypes

Periods are

Arranged horizontally and increasing in atomic number

Groups are

Arranged in vertical columns, they share the same chemical binding characteristics

Isotopes

Are atoms of the same element that have different number of neutrons and different atomic masses

Some isotopes?

Spontaneously decay

Radioactive isotopes

Give off energy in the form of rays and subatomic particles. ex : carbon 14

Electrons are?

Are attracted to positively charged nucleus thus taking energy to hold them in place

Electrons have energy why

Due to their relative position ( potential energy )

Bohr models

Is a useful way to visualize electron location

3 rules for atoms w 20 or less

1) first shell holds 2 electrons

2) second shell holds 8 ( nd so on)

3) each lower shell gets filled first with electrons before placed on the next

Valence shell

The outermost energy shell of an atom

Octet rule

States that the outermost shell is most stable when it has eight electrons

Octet rule exception

If an atom has one shell the outermost valence shell is complete when it has two electrons

The number of electrons

In a atom valence shell determines wether the atom gives up, accepts or shares electrons to get 8 electrons on the outer shell

Chemically stable

Atoms with valence shells filled with electrons

Molecule

Is two or more of the same atom bonded. Smallest part of a compound ( chemical properties) 02 H2 ect

Compound

Is a molecule containing at least two different elements bonded together. CO2, H20, C6H12O6, ect

Formula

Tells the number of each kind of atom in a molecule.

Bonds between atoms in molecules

Contain energy

Bonds between atoms

Are caused by interactions between electrons in the outermost shell

Bond formation

Chemical reaction

Ion

Is an atom that has lost or gained an electron

ionic bond

Forms when electrons are transferred from one atom to another and oppositely charged ions are attracted to eachother

Covalent bond

Results when two atoms share electrons so each atom has an octet of electrons in the outer shell

Nonpolar covalent bond

Electrons are shared equally between atoms. Ex: hydrogen gas

Polar covalent bonds

Electrons are shared unequally. Ex: h2o

Electro negativity

Is the ability of an atom to attract electrons towards itself in a chemical bond

Datons theory 1

All matter is made of atoms which are indivisible

Datons theory 2

All atoms of given element are identical in mass and properties

Datons theory 3

Compounds are combinations of two or more different atoms

Datons theory 4

A chemical reaction is a rearrangement of atoms

Hydrogen bond

Is a weak attraction between a slight positive hydrogen atom & a slight negative atom

Cohesion

Is the ability of water molecules to cling to each other due to hydrogen bonding

Adhesion

Is the ability of water molecules to cling to other polar surfaces

Ice is?

Less dense than liquid water

Water has a

High heat capacity allowing to help with homeostasis

Cohesion and Adhesion account for?

Water transport in plants & blood cells

PH is a measure of?

Hydrogen ion concentration in a solution

Hydrogen ions H+ & Hydroxide ions OH-

Water ionizes or dissociates it releases an equal number of

Acids

Are substance ls that dissociate in water, releasing hydrogen ions

Bases

Are substances that either take up hydrogen ions or release them

pH scale

Is used to indicate the acidity or basicity (alkalinity)

0 < 7

Acidic

7

Neutral

7 > 14

Basic

Each unit change is a

10 fold change