Biology Chapter 2

What are the essential elements?

What makes up 96% of living matter?

A substance consisting of two or more elements combined in a fixed ratio

Has characteristics different from those of its elements

Anything that takes up space and has mass

Substances that cannot be broken down to other substances by chemical reactions

What are organisms composed of?

What is matter made up of?

Are required by an organism in only minute quantities

What does an elements properties depend on?

Consists of a certain kind of atom that is different from those of other elements

The smallest unit of matter that still retains the properties of an element

Atoms of each element are composed of even smaller parts called..

Relevant subatomic particles

Have no electrical charge

Are positively charged

Are negatively charged

Are found in atomic nucleus

Surround the nucleus in a cloud

Atoms of various elements differ in their number of..

The atomic number is..

The sum of protons plus neutrons in the nucleus of an atom

Differ in the number of neutrons and have the same amount of protons

Spontaneously give off particles and energy

Vary in the amount of energy the possess

The capacity to cause change

The energy that matter posseses because of its location or structure

Are reperesented by electon shells

Defined by its electron configuration and distribution

In the outermost, or valence shell of an atom

Determine the chemical behavior of an atom

The three-dimensional space where an electron is found 90% of the time

The sharing of a pair of valence electrons

Consists of two or more atoms held together by covalent bonds

The sharing of one pair of valence electrons

The sharing of two pairs of valence electrons

The attraction of a particular kind of atom for the electrons in a covalent bond

The more electronegative an atom..

When the atoms have similar electronegativities and share electrons equally

When the atoms have differing electronegativities and share the electrons unequally

An attraction between anions and cations

Sometimes strip electrons away from their bonding partners

Electron transfer between two atoms creates..

Atoms with more or fewer electrons than usual

Negatively charged ions

Positively charged ions

Often called salts, which may form crystals

Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atm

Occur when transiently positve and negative regions of molecules attract each other

Reinforce the shapes of large molecules and help molecules adhere to each other

Is determined by the positions of its atoms valence orbitals and is usually very important to its function in the living cell

Determines how biological molecules recognize and respond to one another with specificity

The making and breaking of chemical bonds

Leads to changes in the compostion of matter

Convert reactants to products

An example of a chemical reaction:

Is reached when the forward and reverse reaction rates are equal