Unit A - Chemistry Flashcards
Define atomic number
Number of protons in an atoms - all atoms of an element have the same amount of protons.
Define base
A base is a compound dissolved in water with a pH level higher than 7.
Define compound
A compound is something made up of more than one element.
Define electron
An electron is a subatomic particle with a negative charge.
Define element
An element is a building block that, when combined with other elements, are the building blocks of all of Earth’s materials.
Define energy level
An energy level is a region of space near the nucleus that may be empty or may contain electrons.
Define endothermic
When a substance has an endothermic reaction it absorbs energy.
Define exothermic
When a substance has an exothermic reaction it releases energy, usually in the form of heat, light, or electricity
Define acid
An acid is a compound that dissolves in water to form a solution with a pH level lower than 7.
Define “group” in the context of a periodic table
A group (or family) of elements is a vertical column in the periodic table, there are 18 groups.
Define ion
An ion is an electrically charged atom or group of atoms
Define isotope
An isotope is an atom of an element with a different number of neutrons than another atom of the same element
What is the law of conservation of mass?
The law of conservation of mass states that when a reaction occurs, the total mass of products will be equal to the total mass of reactants.
What is a molecule?
A molecule forms when two or more non-metallic atoms bond together.
Define neutron
Subatomic particle with no electrical charge.
Define nucleus
Dense core of positively charged subatomic particles.
Define period
A period is a horizontal row. There are seven rows.
What is the pH scale?
The pH scale is a measure of acidity.
Define proton
A proton is a positive sub atomic particle located in the nucleus of an atom
Define valence electron
A valence electron is any electron on the outer energy level of an atom.
How does heating food help preserve it?
Heating food temporarily sterilizes it.
How does freezing food help preserve it?
Freezing food preserves it almost indefinitely. The very low temperature prevents the growth of micro organisms that cause decay
Describe J.J. Thomson’s model of the atom
He suggested that an atom was a sphere of positive charge in which negative particles, known as electrons, were embedded.
Describe Rutherford’s atomic model
Rutherford suggested that atoms are mainly empty space through which positive particles could pass as well as a small, positively-charged nucleus. Electrons could only move through the empty space, not through the core.
What is the difference between cations and anions?
Cations are positively charged ions, whereas anions are negatively-charged.
List three properties unique to acidic solutions
Acids are reactant with metals, turns blue litmus paper red, and acids taste sour.
List three properties unique to basic solutions
Basic solutions are non-reactive with metals, are bitter tasting, and turn red litmus paper blue.
Name the four chemical families
Alkali metals, alkaline-earth metals, noble gases, and halogens.
State the octet rule
The octet rule states that atoms bond in such a way as to have eight electrons in their valence energy level (to be like nearest noble gas).
What are some properties of ionic compounds? (4)
High melting point, retention of crystal shape, solubility in water, conductivity in solution.
Explain what makes water polar
Water is polar because it has a negative end and a positive end because of its bent shape and unequal sharing of electrons. Oxygen end is negative, hydrogen end is positive.
How can you name an acid by its compound formula?
H (the symbol for hydrogen) tends to appear one or more times on the left.
COOH may be seen on the right side of the formula.
How can you recognize a base from its formula?
There may be the presence of the hydroxide ion (OH-)
What is neutralization?
Neutralization is the reaction of acids and bases together, stripping away all acidic/basic qualities.
Name two biochemical reactions
Two biochemical reactions are photosynthesis and cellular respiration.
Name the characteristics of chemical reactions
All chemical reactions involve the production of new substances, all reactions involve the flow of energy, and a change of state can be observed.
How do you balance a formula equation?
To balance a formula equation you must ensure that the amount of atoms on the reactant side of the equation and the product side of the equation are equal.
Describe a formation reaction
A formation reaction is when two elements combine to form a compound.
Describe a decomposition reaction
A decomposition reaction is the reverse of a formation reaction. The products are broken down to yield to the reactants.
Describe a hydrocarbon combustion reaction
A hydrocarbon combustion reaction is the reaction between hydrocarbons and oxygen.
Single replacement reaction
A single replacement reaction is when a reactive element reacts with an ionic compound. After the reaction the element ends up in a compound and one of the elements in the reactant compound ends up by itself as an element.
Double replacement reaction
Double replacement reactions commonly occur between two ionic compounds. The ions in the first compound join with the ions from the second compound, this type of reaction often results in the formation of a precipitate.
What is a mole?
A mole is the quantity that chemists use to measure elements and compounds. Each mole contains the number of particles equal to Avogadro’s number.
What is Avogadro’s number?
6.02x10^23
What is the atomic molar mass of an element?
The atomic molar mass of an element is the average mass in grams of one mole of atoms of that element.
