1st Semester Review Chapters 1-4 Flashcards
What are chemical and physical properties? Provide examples of each.
A chemical property describes a substance’s ability to participate in chemical reactions.
Ex) reaction with oxygen/rusting, flammability, rotting
A physical property is something that can be determined without changing the identity of a substance
Ex) texture, state, melting point, boiling point
What is a chemical change?
Chemical changes occur when the identities of the substance change and a new substance or substances are formed
Ex) baking a cake
What is a physical change?
A physical change are changes in which the identity of a substance does NOT change.
Ex) ice melting
Define volume.
the space an object occupies
Define mass.
the quantity of matter in an object
What is density?
mass / volume
(the degree of compactness of a substance)
Define atom.
the smallest unit of an element that maintains the properties of that element
Define pure substance.
Pure substances are substances that are made up of only one kind of particle and have a fixed or constant structure
ex) elements and compounds
Define molecule.
the smallest unit of a substance that keeps all the physical and chemical characteristics of that substance
Define theory.
A plausible explanation of a body of observed natural phenomena
Define law.
A behavior in the natural world that is always true
Define endothermic reaction.
the process in which heat is being absorbed from the environment
ex) a cake is placed into an oven and baked
Define exothermic reaction.
A systems release of heat into the environment
ex) coal burns in a furnace, producing light and heat
Define kinetic energy.
the energy of an object that is due to the object’s motion
Define specific heat.
the amount of heat required to raise the temperature of one gram of that substance by one degree Celsius
Explain the law of conservation of mass.
Mass is neither created nor destroyed in a chemical reaction, it is conserved.
Formula: mass reactants= mass products
Explain the law of conservation of energy.
In any chemical reaction or physical process, energy may change from one form to another, but it is neither created nor destroyed.
Define isotope.
Different atoms of the same element that have the same number of protons but different number of neutrons
What is a period?
A horizontal row of elements in the periodic table that has increasing atomic numbers
What is a group?
a vertical column of elements in the periodic table that share chemical properties
Define alloy.
A homogenous mixture of two or more metals
Define electron shielding.
Inner electrons shield outer electrons from the nucleus
State the periodic law.
The repeating physical and chemical properties of elements change periodically with their atomic number.
Give evidence of chemical changes.
Change in color, formation of bubbles, gas being formed, odor change, temperature change
Define homogeneous mixture.
mixture that has a uniform composition throughout and always has a single phase; a solution
Define heterogeneous mixture.
mixture that does not have a uniform composition and in which the individual substances remain distinct
Define ground state.
the lowest allowable energy state of an atom
In division and multiplication, the answer must not have more significant figures than the ____
Number in the calculation with the fewest significant figures.
Describe precision.
sameness of measurements, agreement among numerical values, reproducibility of measurements
The SI unit for energy is called
joules
What are Mendeleev’s contributions to the periodic table?
modern periodic table, left gaps for elements that were yet to be discovered, arranged the elements according to their atomic weight
What are the names of the electron orbital shapes? How many electrons can be found in each?
s orbital: two electrons, p orbital: six electrons, d orbital: ten electrons, f orbital: fourteen electrons
Describe the structure of the atom based on modern atomic theory.
An atom is a complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus. This nucleus contains most of the atom’s mass and is composed of protons and neutrons
Name the three subatomic particles and given their relative sizes, location in atom, and charges. Which particles make up the mass of the atom?
Protons: nucleus, positive charge, neutrons: nucleus, neutral charge, electrons: negative charge, outside nucleus in shells; protons and neutrons make up the mass of an atom
What is the periodic trend for atomic radius and reactivity?
decreases across a period: due to the increasing attraction between valence electrons and the nucleus
across the period; Increases down a group:the atomic size is increasing, which causes the outer electron shells to be farther away
Name the steps of the scientific method
- Observe
- ask a question
- form a hypothesis
- Experiment
- analyze data
- Conclusion
- report findings
Describe the properties of Alkali Metals
Group 1, Valence electrons 1. Extremely reactive, Reacts with water.
Physical properties: Very soft, easily cut, good conductor of electricity
Describe the properties of Alkali Earth metals
Group 2, 2 valence electrons. Chemical properties: highly reactive, but slightly less reactive than alkali metals
will react to oxygen in the air.
Physical properties: Higher melting points than the alkali metals
Describe the properties of transition elements
groups 3-12
valence electrons vary
chemical properties:
-less reactive than alkali and alkali earth
physical properties:
- Most are solid at room temperature except Hg which is a liquid, good conductors of heat and electricity
Describe the properties of other metals
between 13-16, valence electrons between 3-6.
physical properties: good conductors of heat and electricity
chemical properties:
Some can react to form poisons
Silver/grey in color, Malleable
Easily lose electrons
Describe the properties of non-metals
Non-metals
hydrogen in group one, the rest 14-16
valence electrons between 1-7
chem properties: easily gains electrons
phys prop: Exists at room temperature as a gas or solid
poor conductors of heat and electricity
Describe the properties of noble gasses
Group 18
8 valence electrons (except for He which has 2)
chemical properties
very unreactive (stable)
Only Kr, Xe and Rn have been able to form compounds
Physical properties
colorless
odorless
tasteless
Describe the properties of semiconductors (metalloids)
Semiconductors are the same as the metalloids group from the 4.2a notes.
Metalloids have properties of both metals and nonmetals.
Metalloids are used as semiconductors in electronics.
Can be shiny or dull.
Metalloids conduct heat and electricity better than nonmetals, but not as good as metals.
