advanced science mid term

how many different ways to represent atoms did we learn?

4

what are the 4 different ways to represent atoms?

Bohr-Rutherford, Simplified, Ball and stick, Lewis

in Bohr-Rutherford's model what did the period and groups represent?

period represents the number of electron shells in the atom. group represents the number of valence electrons

in Bohr-Rutherford's model what did The number indicate?

number of electrons and the number of protons

in the simplified model Electrons and protons are placed how?

same as the Bohr-Rutherford model

in the simplified model how were the number?

by subtracting the atomic number from the mass

how are atoms shown in the Ball and stick model?

Atoms are balls, bonds are sticks

ball and stick model is useful for what?

when dealing with molecules of more than one atom

what is the size of the ball in the ball and stick model generally proportional to?

to the number of election shells

what is Lewis model?

Simplified representation that shows the number of valence electrons around the atomic symbol

what model is this?

Bohr-Rutherford

what model is this?

simplified

what model is this?

ball and stick

what model is this?

lewis model

what are the 3 groups that elements can be categorized into?

Metals, Non-metals and Metalloids

what are the 7 properties of metals?

Lustre (shiny), Conduct heat and electricity, Ductile, Malleable (bendable), Dense, Most are solid at room temperature ,Release gas when placed in acid

what are the 7 properties of non-metals?

Dull (not shiny), Poor or non-conductors, Non-ductile, Non-malleable (doesn’t bend) , Low densities, Will not react with acids , Can be gases, liquids or solids

what are Metalloids?

Metalloids are known as the “in between” group. They have some properties of both metals and non-metals. There are only 10 of these.

where are metals found on the periotic table?

are found to the left of the step line on the periodic table.

where are non-metals found on the periotic table?

are to the right of this line.

where are Metalloids found on the periotic table?

cluster right around this line. (the staircase)

how are elements on the periotic table organized?

Elements on the periodic table are organized according to their similar properties. in columns and rows.

what are columns on the periodic table?

(going down on the periodic table) are called groups or families

what are rows on the periodic table?

(going across of the periodic table) are called periods.

what are the Properties of Alkali Metals?

Soft, light metals that melt at low temperatures.
High degree of reactivity, especially with water

what are the Properties of Alkaline Earth Metals?

grey solids, hard, reactive

what are the Properties of Halogens?

corrosive and toxic, very reactive and colored, often forms compounds with other elements.

what are the Properties of Inert (Noble) Gases?

no chemical reactivity, colorless, do not form compounds with other elements.

the period number on the periodic table tells you what?

how many shells an element has.

the family/group number on the periodic table tells you what?

how many electrons on the outer shell electrons on that are called valence electrons.

what is the maximum numbers allowed on the on the outer shell?

8 valence electrons

what is group IA

alkali metals

what is group IIA

alkaline earth metals

what is group VIIA

halogens

what is group VIIIA

inert or noble gases

what are the shell capacities for the Bohr-Rutherford?

1st 2, 2nd 8, 3rd 8, 4th 8

what is the atomic number?

its the top number on the left. it is also the number of protons.

what is the atomic mass?

its the number on the bottom left. mass of protons and neutrons

how much do protons and neutrons weigh?

1 atomic mass unit (amu)

what does an atom need to be neutral?

the number of neutrons and electrons need to be equal

what are isotopes?

same element with different number of neutrons

do different isotopes have the same chemical and physical characteristics?

same chemical but different physical

how do you find the number of neutrons in an atom?

you subtract atomic number from atomic mass

what is matter made of?

Matter is made up of atoms. An atom is the smallest particle of matter. It cannot be divided chemically.

who is Aristotle? what did he propose?

he was a Greek Philosopher 300 BC.

HE PROPOSED THAT:

All matter was continuous –no matter how small a substance was, the original properties were the same.

Matter was made of the four basic elements fire, water, air, earth.

Did not know about atoms.

“No matter how small a substance was, the original properties are the same”

who is Democritus? what did he propose?

he was a Greek philosopher 300 BC.
HE PROPOSED THAT:
Matter was discontinuous
Matter can be broken into smaller particles
Defined the term atom
“Matter can be broken into smaller particles”

out of the two Greek philosophers whos ideas were more excepted?

Despite Democritus’ accuracy, Aristotle’s ideas were more widely accepted.

where any of the philosophers scientists?

no and neither of them did experiments. They were both thinkers and came up with ideas to explain what they saw in the world around them.

who is known as the father of theory?

John Dalton

what were the 4 main points John Dalton formulated about atoms?

all matter is composed of invisible particles called atoms. all atoms of the same element are identical. atoms of different elements are different. during a chemical reaction atoms combine to form new products.

Daltons atomic model today?

his main principle is still true today. his model was modified to explain new observations of later chemists.

what did Thomson discover?

he discovered electrons while experimenting with cathode rays.

what did Thomson believe?

that the atom was a positive sphere with electrons embedded in it like raisins in a plum pudding.

what is a A cathode ray tube?

a sealed evacuated glass tube.

what are Cathode rays?

beams of tiny, negatively charged particles called electrons that flow through this tube.

what did Thomson use the cathode ray tube for?

to discover various properties of cathode rays (electrons)

give the 4 properties of cathode rays?

they travel in a straight line, they drive a small propeller located in their path (this tells us that they have mass). The cathode rays cause the shadow of the object in their path to be projected on a fluorescent screen. he cathode rays are attracted towards the positively charged plate (this shows that they are negative).

what did Ernest Rutherford believe?

the atom had a central positive nucleus surrounded by negative electrons floating around in a cloud like structure. the elections are not organized.

how did Rutherford discover the nucleus?

Rutherford used the ideas of radioactivity to carry out experiments to help him better define the atomic model. his experiment involved Exploring matter by shooting radioactive alpha particles against thin sheets of metal.

who's experiment was this?

Rutherford

explain Rutherford's experiment?

A piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space. Some particles had their paths bent at large angles.

what were Rutherford's 3 observations and the conclusions to them?

most/almost all the went through the gold foil and were not defalcated. this shows that atoms contain a significate amount of empty space. few/not many bounced back meaning the atoms dense core nucleus most be very small. several/some went through the gold foil and were deflected meaning the nucleus must be positive.

explain Rutherford's model?

model based on his findings and Thomson's Model. placed electrons orbiting, like a cloud, around a dense, positively charged nucleus.

how did Neils Bohr improved Rutherford’s model?

by placing electrons in distinct energy levels or “shells” rather than an electron “cloud”

who theories were combined to make the simplified atomic model?

Bohr & Rutherford

The atom is made up of what three sub-atomic particles?

protons, neutrons and electrons

give info on the nucleus?

contains protons and neutrons. overall positive charge. contains nearly all mass (dense).

give info on electrons?

located outside the nucleus. easily moved, lost or gained. negative charge.

symbol= P

atomic number= 15

atomic mass= 30.974

protons=15

neutrons= 16

electrons= 15

how much do protons, neutrons and electrons weigh?

protons= 1 atomic mass unit (amu)

neutrons= 1 amu

electrons= negligable

what do you need for an atom to be neutral?

number of protons= the number of electrons

what are isotopes?

same element with different number of neutrons. They share almost the same chemical properties, but differ in mass and therefore in physical properties and reactivity.

how do you calculate how many neutrons they are from the element?

subtract the atomic number from the atomic mass

where to read the number of protons?

its the atomic number

elements have characteristic properties that allow them to be classified into three groups. what are these 3 groups?

metal, non-metal and d Metalloids

what are 7 properties of metals?

luster (shiny), conduct heat and electricity, ductile, malleable (bendable), dense, most are solid at room temp, release gas when placed in acid.

what are properties of non-metals?

dull (not shiny), poor or non-conductors, non-ductile, non-malleable (not bend), low densities, will not react with acids and can be gases, liquids or solids.

properties of metalloids?

is known as “in-between” groups. they have some properties of both metals and non-metals. There are only 10 of these.

where are metals, non-metals and metalloids found on the periodic table?

metals= found on the left of the step line.

non-metals= are to the right of the line

metalloids= cluster right around the line (the staircase)

how are the elements organized on the periodic table?

according to their similar properties.

what are columns and rows called on the periodic table called?

columns= (going down on the periodic table) are called groups or families

rows= (going across of the periodic table) are called periods.

what are alkali metals properties? where are they placed on the periodic table?

soft, light metals, that melt at low temp. high degree of reactivity especially with water. they are in group 1A

what are Alkaline Earth Metals metal properties? where are they placed on the periodic table?

grey solids, hard, reactive. group 2A

what are properties of halogens? where are they placed on the periodic table?

corrosive and toxic, very reactive and colored, often form compounds with other elements. group 7A (17)

what are properties of inert (noble) gases? what are they placed on the periodic table?

no chemical reactivity, colorless, do not form compounds with other elements. group 8A (18)

what does the period tell you?

it tells you how many energy shells an element has.

what does the family or group tell you?

Tells you the number of electrons in the outer shell (valence electrons)

where are valence electrons found and what is the maximum number?

outermost shell. 8 is the max.

how do you put together the Bohr-Rutherford model?

look for the period of the element that will tells you number of electron shells in the atom. also find group number of valence electrons. the number will indicate number of electrons and protons.


1. place number of protons in middle
2. then draw electron shells as needed around
3. place number of electrons in the appropriate places

how to put together the simplified model?

electrons and protons are placed the same as Bohr-Rutherford’s model. the number of neutrons are found by subtracting the atomic number by atomic mass. number of neutrons go inside with protons.

how to put together ball and stick model?

atoms are the ball and bonds are the sticks. very use full with molecules of more than one atom. the size of the ball is normally proportional to the number of electron shells.

how to put together the Lewis model?

simplified representation that shows the number of valence electrons around the atomic symbol. little dots

notes number 5

what does one mole equal?

1mol= 6.03 times 10 to the power of 23 (6.022 × 10²³)

what do we use to calculate the number of moles in a sample?

the mass of elements

what is molar mass?

the mass of exactly one mole of a given substance.

what is 6.022 × 10²³ called? what is the name based off?

Avogadro’s number it was based off his research of carbon

where can you find molar mass? what unit do you use?

you find it on the periotic table. use grams (g) as the unit

solve the molar mass for H2O

(2x1.011) + 15.99

=18.012

solve the molar mass for NaCl

22\.9898+35.453=58.4428