Chapter 2-3, 2-4 Flashcards
What are the unique properties of an element?
- Color
- Texture
- Melting point
- Color when burned
Element
- The simplest form of matter that ha a unique set of properties
- Serve as the building block for all other forms of matter
- Composed of atoms that have the same number of protons, neutrons, and electrons as all other forms of the element
- Ex: Oxygen v.s Helium
Atom
-A substance that cannot be broken down into simpler substances by chemical means
Proton
-Particles with a positive charge
Neutrons
-Particles with a neutral charge
Electrons
-Particles with a negative charge
Structure of an atom
- Subatomic particles: protons, neutrons, electrons
- Nucleus: is the center of the atom and consists of neutrons and protons
Atoms and the periodic table
- The number of protons an atom has will dictate what element it is
- An atom can have any number of electrons and neutrons but only one number of protons
What ways can atoms be represented?
- Diagram
- Colored circle (Ball and stick modeling)
- Element symbol (C)
Compound
- A substance that contains two or more elements chemically combined in a fixed proportion
- Physical methods are used to separate mixtures that cannot break a compounds into simpler substances
- Ex: Carbon, oxygen, hydrogen are combined to the compound sucrose
Chemical symbol
- Each element is represented by a one or two letter chemical symbol
- First letter= caps, second= lowercase
Periodic Table
-Arranges the elements based on a set of repeating properties
Period
-Each horizontal row of the periodic table
Group
- Each vertical column of the periodic table
- Also called a family
Properties of Compounds
- Different from their compounds elements
- Ex: Sugar= sweet, Carbon= tasteless black solid
- When two compounds are combined, their is a change in composition and a change in properties
- Ex: Sodium chloride (salt) is a white solid
Breaking down compounds
- Electrical current passed through water, broken down into oxygen and hydrogen
- Carbon cannot be broken down into simpler substances
Subatomic Particles
- Particles that are smaller than atoms.
- Protons, Electrons, Neutrons
Nucleus
- Center of the atom
- Consists of neutrons and protons
Lewis Structures (Lewis Dot Structure)
- Used complex molecules are being represented
- Representations of molecules in which an atoms elemental symbol and solid lines are used to represent the components of a molecule.
Chemical Change
- A change that produces matter with different composition than the original matter
Who created chemical symbols?
- Swedish Chemist Jons Jacob Berzelius (1779-1848)
Chemical Property
- The ability of a substance to undergo a specific chemical change
- Can be observed only when a substance undergoes a chemical change
Chemical Reaction
-The process of how one substance becomes one or more new substances
Four signs of chemical change
- Transfer of Energy
- Change in Color
- Production of a gas
- Formation of a precipitate
Precipitate
- A solid that forms and settles out in a liquid mixture
- Occurs during some chemical changes
Law of Conservation of Mass
- During any physical change or chemical reaction, mass is conserved
- Mass is neither created or destroyed
