CHEMISTRY: ATOMIC STRUCTURES, ISOTOPES, IONS, AND THE PERIODIC TABLE

Question 1

Chemistry

Answer 1

The study of matter, which is a substance that has mass and occupies space

Question 2

Substance

Answer 2

Any material all samples of which have the same composition and properties (a mixture is not a substance)

Question 3

Matter

Answer 3

All matter is made up of atoms, and the properties of matter can be explained by the atoms making it up

Question 4

Atom

Answer 4

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

Question 5

What three subatomic particles do atoms contain?

Answer 5

-protons
-neutrons
-electrons

Question 6

[atoms subatomic particles]
Protons

Answer 6

Carry a positive charge and are found in the nucleus of an atom

Question 7

[atoms subatomic particles]
Neutron

Answer 7

Are neutral and are found in the nucleus of the atom

Question 8

[atoms subatomic particles]
Electrons

Answer 8

Carry a negative charge and are found outside the nucleus and arranged according to their energy level

Question 9

Element

Answer 9

Identified by its symbol and its atomic number

Question 10

Atomic number

Answer 10

Atomic number is equal to the number of protons found in the nucleus of each of its atoms

Question 11

Mass number

Answer 11

-the mass number of an atom is equal to the number of nucleons (protons + neutrons) in its nucleus
-to find the number of protons in an atom, just look at its atomic number
-for the atom to be neutral, the number of electrons must = the number of protons
-to find the number of neutrons in an atom, subtract the atomic number from the mass number of the element
-sometimes atoms of the same element can be found with different mass numbers and therefore with different numbers of neutrons (the number of protons never changes because that would make the atom a different element. Ex. nitrogen always has five protons and carbon always has six protons)

Question 12

Isotopes

Answer 12

-Atoms of the same element (with the same number of protons) that contain a different number of neutrons are called isotopes
-Ex. carbon–14, the notation “14“ before the element symbol, is the mass number of the isotope; it equals the number of protons and neutrons
-since carbon has six protons, carbon 14 has eight neutrons (14-8)

Question 13

Atomic mass

Answer 13

-atomic mass of an element is a weighted average of the mass numbers of all naturally occurring isotopes of the element

Question 14

Radio-isotopes

Answer 14

-some isotopes are radioactive, these are called radio-isotopes
-ex. a treatment of thyroid cancer uses I, a radio-isotope of iodine, which is transported to the thyroid gland

Question 15

Ions

Answer 15

-when the number of electrons does not equal the number of protons, the atom carries a charge
-charged atoms are called ions
-ex. a neutral sodium atom has 11 protons and 11 electrons however, a sodium ion (Na+), which forms by losing an electron, has 11 (positively charged) protons and 10 (negatively charge) electrons
-losing an electron is the same as losing one unit of negative charge
-the sodium ion therefore has a + after it: Na+
-an ion with a positive charge is called a cation
-an ion with a negative charge is called an anion; it has more electrons than protons

Question 16

[ions]
Cation

Answer 16

An ion with a positive charge

Question 17

[ions]
Anion

Answer 17

An ion with a negative charge; it has more electrons than protons

Question 18

Energy levels

Answer 18

-electrons are found at different energy levels of an atom
-electrons found in the outermost energy level are called valence electrons
-elements with small atomic numbers may have a maximum of two valence electrons; all other elements may have a maximum of eight valence electrons

Question 19

Periodic table

Answer 19

-the periodic table contains all the known elements, arranged in horizontal rows called periods, in order of increasing atomic number
-the columns, or groups, on the table contain elements with similar properties because of their similar electron configurations
-from left to right across a period, the elements move from metals on the left-hand side of the chart to metalloids and finally to nonmetals on the right-hand side
-the last group on the right is the noble gases, which have full valence shells and are inert (not chemically reactive)
-there are many more metals than nonmetals