Chapter 2 - General Biology/Biological Science

Water molecules are attracted to each other due to the opposite charges created by partial charge separations within the molecules. These attractions are called:

 

hydrogen bonds

Salt is often used to melt ice on roads during the winter because it lowers the freezing/melting point of water.  When salt dissolves in water, individual Na⁺ and Cl^- ions break away from the salt lattice and become surrounded by water molecules. Why would this cause ice to melt?

Hydrogen bonds are broken, and the salt ions interfere with interactions between H and O. As a result, it is more difficult for water molecules to bond and form ice.

Which element's isotope is commonly used to determine when biological samples such as fossils, were formed?

carbon

Which atomic particle has no charge and is located in the nucleus?

neutron

Atoms containing a specific number of protons are called:

elements

Isotopes that are unstable and decay when their nucleus breaks up into elements with lower atomic numbers, emitting significant amounts of energy in the process, are called:

radioactive

Atoms in which the number of electrons does not equal the number of protons are known as:

ions

Water molecules are polar with ends that exhibit partial positive and negative charges. These opposite charges allow water molecules to attract each other through:

hydrogen bonds

How many hydrogen bonds can a water molecule form?

4

Life is thought to have evolved from complex molecules formed by the interaction of smaller molecules in oceans and the atmosphere. The substance which brought these molecules together to interact is

water

what is an element?

a substance that cannot be broken down into other substances by ordinary chemical procedures

what is a compound?

a substance made of two or more elements in fixed ratio

what are the four elements that make up 96% of living matter?

C, H, O, N

what is a trace element?

elements required by an organism in only minute quantities

what is an example of a trace element ?

Fe and I (iron and iodine)

what is an atom?

The tendency of water molecules to stick together is called __________.

cohesion

substances that cannot be broken down into other substances are called?

elements

silicon has an atomic number of 14 and a mass of 28. How many neutrons are found in silicon?

14

what is the pH inside most living cells?

pH 7

a substance that resists changes in pH is referred to as a ?

buffer

what is the term for an atom that is electrically charged as a result of gaining or losing electrons?

ion

in an atom with a neutral overall charge, the number of protons is equal to the ?

number of electrons

an ionic bond involves ?

an attraction between ions of opposite charge

in salt, what is the nature of the bond between sodium and chlorine?

ionic

substances that contain two or more elements in a fixed ratio are called?

compounds

an uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. how many protons does boron have?

5

what atoms have the same atomic number but different atomic masses?

isotopes

what subatomic particle has a mass of ~1 amu

neutron and proton

what subatomic particle has a mass of ~1/2000 amu

electron

The innermost electron shell of an atom can hold up to _____ electrons.

2

What determines the types of chemical reactions that an atom participates in?

the number of electrons in the outermost electron shell

What are atoms with the same atomic number but different atomic masses?

isotopes

A(n) _____ refers to two or more atoms held together by covalent bonds.

molecule

What name is given to the bond between water molecules?

hydrogen

In salt, what is the nature of the bond between sodium and chlorine?

ionic