What are the building blocks of all matter?
Atoms
All substances are made of tiny particles of matter called atoms.
What are the subatomic particles that make up an atom?
- Protons
- Neutrons
- Electrons
Each atom is made of these three types of particles.
Where are protons and neutrons located in an atom?
Nucleus
The nucleus is the center of the atom.
What is the mass of an electron compared to protons and neutrons?
Negligible
The mass of an atom is primarily contained within the nucleus.
What is the relative atomic mass based on?
Carbon-12 atom
One relative atomic mass unit is equal to 1/12th the mass of a carbon-12 atom.
What is the relative atomic mass of hydrogen?
1
This means that 12 atoms of hydrogen have the same mass as 1 atom of carbon.
What is the charge and relative mass of a proton?
- Charge: 1+
- Relative Mass: 1
Protons are positively charged particles.
What is the charge and relative mass of a neutron?
- Charge: 0 (neutral)
- Relative Mass: 1
Neutrons have no charge and are found in the nucleus.
What is the charge and relative mass of an electron?
- Charge: 1-
- Relative Mass: 1/1840
Electrons are negatively charged particles.
The atomic number (or proton number) is defined as what?
Number of protons in the nucleus
The symbol for atomic number is Z.
What does the mass number (nucleon number) represent?
Total number of protons and neutrons
The symbol for nucleon number is A.
How do you calculate the number of neutrons in an atom?
Mass number - Number of protons
Protons and neutrons can collectively be called nucleons.
What is the relationship between atomic number and electrons in a neutral atom?
They are equal
A neutral atom has the same number of protons and electrons.
How can you find the number of protons in an unknown element?
Using its atomic number
All atoms of the same element have the same number of protons.
What is the formula to find the mass number?
Number of protons + Number of neutrons
This helps in determining the composition of an atom.
Elements
A substance made of atoms that share the SAME number of protons and cannot be broken down into simpler substances by chemical methods. There are 118 elements in the periodic table, such as sodium.
Compounds
Two or more elements chemically bonded together (in a fixed proportion). e.g. Carbon Dioxide, Sodium Chloride
Mixtures
Two or more elements not chemically bonded together. e.g. Sand and Water, Oil and Water
Atomic Structure
All substances are made of tiny particles called atoms, the building blocks of all matter. The structure of the atom has a central nucleus containing neutrons and protons surrounded by electrons in shells.
Subatomic particle
Relative Mass Relative Charge
Proton 1 +1
Neutron 1 0
Electron 1/1840 -1
Overall charge of the atom
Since electrons and protons have opposing and equal charges, the atom’s overall charge is neutral.
Purpose of neutrons
Neutrons have the purpose of holding the nucleus together. The larger the nucleus gets, the more neutrons are required to hold the nucleus together.
Why is an Atom neutral in Charge?
As the number of positive protons are equal to the number of negative electrons.
What is another name for Proton Number?
Atomic Number
