Chapter 1 Elements and the Periodic Table Flashcards
What is the atomic theory?
All matter is made up of tiny particles called atoms.
What is an atom?
A neutral particle with a nucleus, the smallest sample of an element.
What is the nucleus of an atom?
The dense central structure, which contains most of the atom’s mass. An atom is mostly empty space.
What is the nucleus made up of?
Protons and neutrons.
What is a proton’s charge?
Positive.
What is a neutron’s charge?
Negative.
Where are electrons found in an atom?
In the empty space around the nucleus.
How much do electrons weigh?
An electron weighs 1/1837 the weight of a proton, so its relative mass is 0.0005.
What are subatomic particles?
The particles in atoms, protons, neutrons, and electrons.
Why are atoms neutrally charged?
They have the same number of protons, neutrons, and electrons.
What is an element?
A pure chemical species consisting of atoms of a single type.
How many different types of elements are there?
118.
How are elements defined?
By the number of protons in their nucleus.
How are elements of each element classified?
By the number of subatomic particles.
What is a molecule?
A group of atoms bonded together covalently. Can be either the same elements, or different elements.
What is a compound?
A substance consisting of two or more elements. Not all compounds are molecules.
How are elements represented?
With the element symbol, and then the atomic number and mass number.
What is an element symbol?
The simplified representation of an element consisting of 1 or 2 letters
What is the atomic number?
The number of protons in the nucleus of a particular element. (Symbol Z)
How can you find the number of electrons in a neutrally charged atom?
Since atoms are neutrally charged, they will have the same amount of protons and electrons, so the amount of electrons will be the same as the atomic number.
What is the mass number?
The total number of protons and neutrons in the nucleus of a particular isotope of an element. (Symbol A)
How are elements arranged by atomic number in the periodic table?
They are arranged in order of increasing atomic number.
