6.1-6.4 Flashcards
What is matter composed of?
Tiny particles called atoms.
What are atoms?
The building blocks of matter.
What are atoms made of?
Smaller particles called neutrons, protons, and electrons.
What are the charges of protons, neutrons, and electrons?
Protons are positively charged particles
Neutrons are particles that have no charge
Electrons are negatively charged particles
Where are protons and neutrons located?
In the center of the atom, called the nucleus
Where are electrons located?
Outside the nucleus
What is an element?
A pure substance that cannot be broken down into other substances by physical or chemical means.
How many known elements are there?
100.
How many elements occur naturally?
92
What are horizontal rows called?
periods
What are vertical columns called?
groups
What are isotopes?
Atoms of the same element that have the same number of protons and electrons but have a different number of neutrons.
What does changing the number of neutrons in an atom affect?
Its stability.
What happens when a nucleus breaks apart?
It gives off radiation that can be detected and used for many applications.
What are isotopes that give off radiation called?
Radioactive isotopes
What are compounds?
Pure substances formed from a specific combination of two or more different elements in a fixed ratio.
Compounds can only be broken down into simpler compounds or elements by chemical means.
What is a chemical bond?
The force that holds substances together.
What is responsible for forming chemical bonds?
The electrons of an atom.
What are energy levels?
Areas around the nucleus in which Electrons travel around.
How do atoms become more stable?
By losing electrons or attracting electrons from other atoms.
What are covalent bonds?
Chemical bonds that form when electrons are shared.
What are molecules?
Electrically neutral groups of two or more atoms held together by chemical bonds.
Molecules are distinguished from ions by their lack of electrical charge
What are ions?
Atoms that has lost or gained one or more electrons.
Ions carry an electric charge.
What are ionic bonds?
Electrical attraction between two oppositely charged atoms.
Which two types of elements tend to donate or accept electrons more easily than other atoms?
Metals tend to donate electrons and nonmetals tend to accept electrons.
What are the properties of ionic compounds?
Most ionic compounds dissolve in water, are crystalline at room temperature, and have higher melting points than compounds formed by covalent bonds.
What are van der Waals forces?
Attractions between molecules.
How do van der Waals Forces work?
When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.
The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons.
What are the forces that are responsible for water droplet formation and surface tension?
van der Waals forces.
How do van der Waals Forces cause water droplet formation and surface tension?
The slightly positive and slightly negative charges around the water molecule are attracted to the opposite charge of other nearby water molecules.
How are the particles that make up atoms diagrammed?
The protons, neutrons, and electrons are represented by different colored spheres. They are differentiated according to color. The protons and neutrons are in the center of the diagram. Electrons are placed around the nucleus (containing the protons and neutrons) in a cloud formation representing energy levels.
What are the similarities between covalent and ionic bonds?
Both ionic and covalent bonds create molecules.
How are van der Waals forces described?
Van der Waals forces are attractions between molecules and are responsible for water droplet formation and surface tension.
What are the roles of chemical reactions in life?
Chemical reactions allow living things to grow, develop, reproduce, and adapt.
What are chemical reactions?
The process by which atoms or groups of atoms in substances are reorganized into different substances.
Chemical bonds are broken or formed during a chemical reaction.
What are clues that a chemical reaction has taken place?
Production of heat or light
Formation of a new gas, liquid, or solid
How might physical reactions be confused with chemical reactions?
Substances can also undergo physical changes, which change the appearance but not the composition.
How do written chemical equations work?
Chemical formulas describe the substances in the reaction and arrows indicate the process of change.
What are reactants?
The starting substances on the left side of the arrow.
What are products?
The substances formed during the reaction on the right side of the arrow.
What can the arrow in chemical equations be read as?
The arrow can be read as “yields” or “react to form.