CHAPTER 2-4

Question 1

Express very large and very small numbers using scientific notation.
EX: 578000000, 0.0000000098

Answer 1

5.78x10^8
9.8x10^-9

Question 2

Report measured quantities to the correct number of digits.

Question 3

Determine which digits in a number are significant.
EX: 0.000456, 7096, 495.00

Answer 3

AS: 3,4,5

Question 4

Round numbers to the correct number of significant figures.

Question 5

Determine the correct number of significant figures in the results of multiplication and division calculations.

Question 6

Determine the correct number of significant figures in the results of addition and subtraction calculations.

Question 7

Determine the correct number of significant figures in the results of calculations involving both addition/subtraction and multiplication/division.

Question 8

Convert between units.

Question 9

Convert units in a quantity that has units in the numerator and the denominator.

Question 10

Convert units raised to a power.

Question 11

Calculate the density of a substance.

Question 12

Use density as a conversion factor.

Question 13

Classify matter as element, compound, or mixture.

Answer 13

-There are two types of matter pure substance and mixtures.
-Pure substances (have only one type of atom or molecule) are either elements or compounds
-elements cant be broken down into simpler substances by chemical processes, elements of the periodic table
-compounds are 2 or more elements chemically united (bonded) in fixed/definite proportions, and can be decomposed into simpler substances (ex: H2O)
-mixtures have two or more atoms/ molecules, in different proportions; the two types are homogeneous and heterogenous
-homogeneous are uniformed throughout (ex: air, sea water
-heterogenous are non-uniform (ex: oil & water, smoke)

Question 14

Distinguish between physical and chemical properties.

Answer 14

-Physical properties: properties a substance displays without changing its composition
EX: Oder, density, size, shape,mass, boiling point
-chemical properties: properties a substance can display only by changing its composition
EX: flammability, iron rusting, corrosion

Question 15

Distinguish between physical and chemical changes.

Answer 15

-physical changes: change that affects only the appearance of a substance not its chemical composition
EX: solid<->liquid<->gas, grind metal -> powder
-chemical changes: change in which matter changes composition -> new substance
EX:chemical reaction occurring (reactants[A+B]—-> products[C+D])

Question 16

Apply the law of conservation of mass.

Answer 16

Matter is neither created nor destroyed
Mass of reactants = mass of products

Question 17

Identify and convert among energy units.

Answer 17

-Energy types: the capacity to do work -> results of a force acting on a distance
-total energy = kinetic energy + potential energy
-kinetic energy: the energy associated with motion
-potential energy: the energy associated with the position of matter.

Question 18

Convert between Fahrenheit, Celsius, and Kelvin temperature scales.

Question 19

Perform calculations involving transfer of heat and changes in temperature.

Question 20

Recognize that all matter is composed of atoms.

Answer 20

John Dalton’s Atomic Theory
-elements are made of tiny particles called atoms
-all atoms of a given element are identical
-atoms of a given element are different from those of any other element
-atoms of one element. Combined with atoms of other element to form compounds
-atoms are not created or destroyed in chemical reactions

Question 21

Explain how the experiments of Thomson and Rutherford led to the development of the nuclear theory of the atom.

Answer 21

1897
-electrons are negatively charged
-electrons are much smaller & lighter than atoms
-electrons are uniformly present in different types of substances
*atoms have to have positive charges that balances out the negative charges of electrons
-plum pudding electrons in a sphere of positive charge (no concentrated area of positive charge)
-Rutherford attempted to prove the plum model, using a detector and a gold foil with a source from lead
-a few particles were deflected at large angles but most particles passed right through the foil
-most of the atom’s mass & all its positive charge are contained in a small core the nucleus
-most of the volume of the atom is empty space through which tiny negatively charge electrons are dispersed
-the number of negatively charged electrons outside the nucleus is equal to the number of positively charged particles (protons) inside the nucleus -> electrically neutral

Question 22

Describe the respective properties and charges of electrons, neutrons, and protons.

Answer 22

Proton - positively charged nuclear particles
Neutron - a nuclear particle with no electrical charge and has about the same mass as proton
-negative and positive particles attract, positive and positive or negative and negative repel

Question 23

Determine the atomic symbol and atomic number for an element using the periodic table.

Question 24

Use the periodic table to classify elements by group.

Answer 24

-Metals are located on the left side
Properties conductors, malleable, ductile, shiny, metals tend to lose electrons when they undergo chemical changes
-non metals are located on the right of the zig zag line
Properties some are solid at room temp, others are gases, poor conductors, tend to gain electrons when they undergo chemical changes
-metalloids are located along the zig zag line
Properties intermediate between metals and non metals, semi conductors

Alkali metals(soft & very reactive) are on the far left column then comes the alkaline earth metals (less reactive little harder) after you pass the transition metals then some other metals and non metals. The far right column is noble gases(least reactive very stable) and next to it are halogens(very reactive).

Question 25

Determine ion charge from numbers of protons and electrons.

Answer 25

Ion charge = #p - #e

Question 26

Determine the number of protons and electrons in an ion.

Answer 26

You can predict the charge from the position of the element in the periodic table relative to the noble gases.

Question 27

Determine atomic numbers, mass numbers, and isotope symbols for an isotope.

Answer 27

Isotopes are atoms with the same number of protons but different number of neutrons
Mass number = #p + #n
Atomic number = # of protons

Question 28

Determine number of protons and neutrons from isotope symbols.

Answer 28

A -> mass number
X -> element symbol
Z -> atomic number

Question 29

Calculate atomic mass from percent natural abundances and isotope masses.

Answer 29

(fraction of isotope 1 x mass of isotope 1) + (fraction of isotope 2 x mass of isotope 2) + …

Question 30

Distinguish between exothermic and endothermic reactions/processes.

Answer 30

-exothermic reaction energy is released, heat goes from the system to the surrounding
-endothermic reaction you have to put energy into the reactants, absorbed (energy) heat from the surrounding causing the surroundings will be cooler