Chapter 2.1 The Nature Of Matter Flashcards
Made the concept of an atom
Democritus
Basic unit of matter
Atom
What are the subatomic particles that make up an atom?
Protons, neutrons, and electrons
Positively charged particles
Protoms
Negatively charged particles
Electrons
Particles that have no charge
Neutrons
The center of an atom; made up of protons and neutrons
Nucleus
Where and what are electrons doing in an atom?
They are an orbit around the nucleus, and the are in constant motion
What are electrons attracted to?
The positively charged nucleus
Why are the electrons outside of the nucleus?
Because of the energy of their motion
Are electrons and protons even or uneven?
Even
A pure substance that consists entirely of one type of atom
Element
How many atoms are known? How many are found in living organisms?
There over 100 atoms, and about two dozen are found in living organisms
Atoms of the same element that differ in the number of neutrons they contain
Isotopes
What makes up an atom’s mass number?
The total number of protons and neutrons
What do you identify isotopes by?
Their mass number
Why do all isotopes of an element have the same chemical properties?
Because they have the same number of electrons
What are the ways we use radioactive isotopes?
We use it to determine the ages of rocks and fossils by analyzing the isotopes found in them. We also use them to detect and treat cancer and to kill bacteria that cause food to spoil
A substance formed by the chemical combination of two or more elements in definite proportions
Chemical compound
How do scientists show the composition of a compound?
They use the chemical formula
What is a compound?
The combining of two or more elements
In what ways do compounds differ from their component elements?
The physical and chemical properties of a compound are usually very different from those of the elements from which it is formed
What holds compounds together?
Chemical bonds
What are the two main types of chemical bonds?
Ionic bond and covalent bonds
What are the type of electrons that allow bonds to happen?
Valence electrons
Formed when one or more electrons are transferred from one atom to another.
Ionic bond
Positively or negatively charged atoms
Ions
Moving electrons travel about the nuclei of both atoms
Covalent bond
When two atoms share two electrons it is called a _____
Single covalent bond
When atoms share 4 electrons, it is called a _____
Double bond
Atoms that share 6 electrons are called _____
A triple bond
The structure that results when atoms are joined together by covalent bonds
Molecule
The smallest unit of most compounds
Molecule
When atoms of the same element join together, what do they form?
A molecule
Why can’t all elements join together?
Because of their structures
