Atomic Basics
What is an atom?
The smallest part of an element.
Which particle has a positive charge?
protons
What does the atomic number tell you?
The number of protons.
What is an isotope?
The same element with a different mass number.
I have 11 protons. What element am I?
Sodium (Na)
What is the center of an atom called?
nucleus
Which particle has no charge?
neutron
How many protons does oxygen (O) have?
8 protons.
What stays the same in isotopes of one element?
The number of protons.
I have 17 protons. What element am I?
Chlorine (Cl).
What two particles are found in the nucleus?
Protons and neutrons.
Which particle is negatively charged?
electron
Sodium-23: What is the mass number?
23.
In iodine-127, what does 127 represent?
The mass number.
I have 53 protons. What element am I?
Iodine (I).
Where do electrons move in an atom?
The electron cloud.
Which two particles have about 1 amu of mass each?
Protons and neutrons.
Chlorine-35 has 17 protons. How many neutrons?
18 neutrons (35 − 17).
Lithium-6 and lithium-7 differ in which particle?
Neutrons
What charge does a neutral atom have?
Answer: 0 (no overall charge).
Why are electrons not counted in the mass number?
Their mass is extremely small compared with protons and neutrons.
A neutral lithium atom has 3 protons. How many electrons?
3 electrons
Cesium-133 has 55 protons. How many neutrons?
78 neutrons (133 − 55).
Oxygen-18 has 8 protons. How many neutrons?
10 neutrons (18 − 8).
What is the average atomic mass on the periodic table?
The average mass of an element’s isotopes.