question

sig fig zeros

answer

1. zeros at beginning NOT signif 2. zeros between ARE SIGNIF 3. zeros at end of number are signif if number contains a decimal point

question

3.489 x (5.67-2.3)

answer

3.489 x 3.(3)7 11.75793 12

question

matter

answer

composed of mass and must occupy space

question

scales of matter

answer

macroscopic, microscopic, particulate. scientists think on a particulate scale, observe macroscopically

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states of matter

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1. change from solid to liquid to gas as temp increases 2. motion of particles increase as temp increases 3. distance between particles increases as temp increases

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matter

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-pure substance 1. element 2. compound -mixtures 1. homogeneous 2. heterogeneous

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physical properties

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the atoms or molecules in the matter do not change (color, taste, melting point, boiling point, odor, density)

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chemical properties

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molecules react, composition of matter changes (flammability, oxidation, corrosiveness)

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physical changes

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appearance change but not comp (change in state, change in shape)

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chemical changes

answer

chem reaction occurs, so comp changes... reactants and products

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mass is always conserved

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matter can not be created nor destroyed

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energy

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the other main component of our universe, if something has energy it can do work

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energy is also conserved

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it can be transformed or converted to a different form but the total energy stays the same

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4 energy types

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kinetic potential chemical electrical

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calorie

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amount of energy to raise temp of 1 gram of water by 1 degree Celsius

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1 calorie = ? J

answer

4.184 J = ? cal

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energy and chemical changes

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1. chemical reactions often have associated energy changes 2. reactions that give off heat = exothermic (burning) 3. reactions that absorb heat = endothermic (chem ice pack)

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as temp increases the movement of the atoms or molecules in the substance increase

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-move fastest in gas phase -molecules in a solid don't move they just vibrate around a fixed point

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heat is...

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a transfer of energy between 2 temps

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physical changes require...

answer

energy

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liquid to gas is

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endothermic, water is gaining energy from the surroundings

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gas to liquid is

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exothermic, heat is given off

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water melts

answer

273 K

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water boils

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373 K

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heat capacity

answer

1. all substances change temp when they absorb and give off heat (the amount of change varies between substances) 2. heat capacity shows how much energy needed to raise temp of a substance 1 degree cel 3. water has a very high heat capacity (changing temp has a lot of energy)

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Dalton

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-each element made of indivisible particles called atoms -all atoms of a single element have the same mass which are different from other elements -atoms combine in single whole ratios to form compounds

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Thompson

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found the electron -plum pudding model -believed subatomic particles made up atoms

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Rutherford and gold foil

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shot alpha particles at gold foil and predicted that all would pass through, some bounced back!

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a real atom...

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1. mostly empty space 2. dense core of protons and neutrons 3. cloud of electrons

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to sum up the sizes of p, e, n

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protons and neutrons have almost identical masses and make up the positive nucleus while electrons have almost no mass and a negative charge

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amu

answer

100 amu = 1/12 carbon 12 atom

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matter is usually neutral

answer

number of electrons and protons are equal

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elements are defined by # of protons

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aka atomic number

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atoms do vary in mass

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mass number = protons and neutrons (the nucleus)

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isotope

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different number of neutrons

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left v. right

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metals on left. non metals on right. staircase with metalloids on either side

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1A

answer

alkali metals, lose 1 electron

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2A

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alkaline earth metals, lose 2 electron

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3A

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lose 3 electrons (except B)

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5A

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gain 3 electrons

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6A

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gain 2 electrons

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7A

answer

halogens, gain 1 electron

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8A

answer

noble gases

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protons-electons=

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charge

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Ag is always

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+1

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Zn is always

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+2

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how do ions form?

answer

atoms can form ions by gaining or losing electrons

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main group elements what does group # represent?

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group # represents # of outer electrons

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diatomic molecules

answer

Br, O, H, F, Cl, I, N

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cation

answer

positive ion

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ion

answer

charge elements

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anion

answer

negative ion, have an ide ending

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transition elements...

answer

can form more than one ion, if so this is designated with roman numerals

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compounds are represented by chemical formulas

answer

formula has symbol for each element with a subscript for # of atoms

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chemical formulas start with the most metallic elements first

answer

move from left to right. H position is unpredictable, depends on compound.

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molecular

answer

no metal elements

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ionic

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have a metal

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molecular/ non metal

answer

use prefixes if more than one of an element is present. mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca

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ionic / metal

answer

2 types. 1. the charge of the metal is known 2. the charge of the metal is unknwon

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ionic, charge known

answer

1A, 2A, most of 3A. just say it how it is

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ionic, charge NOT known

answer

use roman numerals for metals that can have different charges. the positive charges on the metal equal to the negative charge on the group 7A/8A element

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chromium (III) oxide

answer

Cr3+ does NOT = O2- so cross multiply, must have 2Cr and 3O so that they both total 6, so Cr2O3

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polyatomic ions

answer

more than one element forms an ion, these atoms move as a unit, just like the single element ions

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using polyatomic ions

answer

use parentheses, to keep the ion together if it is multiplied

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polyatomic ions with hydrogen in the name

answer

they have one more H, and one less charge than the parent ion

question

polyatomic ions ate vs. ite

answer

ate has one more Oxygen than ite

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