BIO 151 Chapter 2.1
An electrically neutral atom has an atomic number of 11 and an atomic mass of 23. This atom has 1.____ protons, 2. _____ neutrons, and 3. ______ electrons.
1. Eleven 2. Twelve 3. Eleven
An electrically neutral atom has an atomic number of 6 and an atomic mass of 14. This atom has 1.___ protons, 2.______ nuetrons, and 3. ______ electrons.
1. Six 2. Eight 3. Six
Atoms with a net positive charge are called...
Cations
The number and configuration of electrons determines an element's ...
Chemical properties
For any given isotope, such as C-14, the rate of decay can be described as which...
Constant
How does the decay of rate of different radioactive isotopes compare?
Different radioactive isotopes decay at different rates.
If an atom gains or loses an ____, it acquires a net electrical charge and becomes and ion.
Electron
Atoms are composed of central nucleus which is surrounded by which orbiting particles?
Electrons
subatomic particles called ___ can be found at various distances from the nucleus
Electrons
It takes work to keep electrons in their orbitals due to the following?
Electrons are attracted to the nucleus.
When electrons move closer to the nucleus
Energy is released
____ atoms always have one proton
Hydrogen
Atom in which the number of electrons does not equal the number of protons are called ___?
Ions or ion
By determining the ratio of the different ___ of carbon and other elements in a sample, scientists are able to accurately determine the age of the sample.
Isotopes
Electrons are attracted to the positive charge of the nucleus, therefore, which of the following is true?
It takes work to keep them in the orbitals.
Electrons that are closer to the nucleus always have...
Less potential energy
Dalton
MASS!!!! A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu.
Almost all the mass of an atom is located in which?
Nucleus
Atoms of the same element have the same number of ___ in the nucleus, and this number is unique for that element.
Protons
All atoms are composed of several types of ___ particles. A proton is an example of such a particle.
Subatomic
The different energy levels of electrons within atoms can be described as...
They can only take certain discrete values that correspond to quanta.
Which correctly describes electrons within atoms?
They occupy discrete energy levels.
How are ions formed?
When atoms lose or gain electrons
atoms with a negative charge
anions
anything that has mass and takes up space
matter
Electron ____ represent probability distributions for electrons, that is regions surrounding the nucleus where there is the highest probability of finding electrons.
orbitals or clouds
Which subatomic particles are located in the nucleus of an atom?
protons and neutrons
_____ isotopes are often used to label or "tag" specific molecules and then follow their progress either in a chemical reaction or in living cells and tissues.
radioactive or radio
atomic number
the number of protons in the nucleus of an atom
no orbital can contain more than ___ electrons
two
What do we call a substance that cannot be broken down into simpler substances by ordinary chemical means?
An element
if two atoms have the same number of protons in their nucleus, you can conclude for sure that they...
Are atoms of the same element.
