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Matter and Change
• What is Chemistry?• Scientific Method• Properties of the States of Matter• Properties and Changes in Matter• Conservation of Mass and Energy• Classifications of Matter• Introduction to the Periodic Table
What is Chemistry?
Chemistry is the study of the composition, structure, and properties of matter and the changes it undergoes.
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What are the Six Branches of Chemistry?
1. Organic Chemistry
2. Inorganic Chemistry
3. Physical Chemistry
4. Analytical Chemistry
5. Biochemistry
6. Theoretical Chemistry
The six branches of chemistry often overlap.
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Organic Chemistry
Organic Chemistry is the study of most carbon containing compounds.
An organic chemist might:• create and analyze new chemicals made from carbon-
containing building blocks.
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Back to Branches of Chemistry
Inorganic ChemistryInorganic Chemistry is the study of all substances not classified as organic chemicals, which includes the chemistry of all substances containing elements other than carbon.
An inorganic chemist might:• study and develop new materials to improve existing
products or make new ones• determine ways to strengthen or combine materials or
develop new materials for use in a variety of products
This year you will be learning inorganic chemistry.
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Back to Branches of Chemistry
Physical Chemistry
Physical Chemistry is the study of the properties and changes of matter and their relation to energy.
A physical chemist might:• develop new types of instruments to measure data.• measure the amount of energy released or absorbed in
chemical processes• study the mechanisms in which chemical reactions
occur
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Back to Branches of Chemistry
Analytical Chemistry
Analytical Chemistry is the identification of the components and composition of materials.
An analytical chemist might:• make measurements and calculations to solve
laboratory and math-based research problems• analyze the composition of medicines and research
new combinations of compounds to use as drugs
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Back to Branches of Chemistry
Biochemistry
Biochemistry is the study of the substances and processes occurring in living things
A biochemist might:• identify enzymes and determine reaction mechanisms
for biochemical reactions• develop new foods, flavors and preservatives, and
study how vitamins and minerals are used in the body.• develop new drugs and study their effects.
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Back to Branches of Chemistry
Theoretical Chemistry
Theoretical Chemistry – the use of mathematics and computers to understand the principles behind observed chemical behavior and to design and predict the properties of new compounds.
A theoretical chemist might:• use a computer to explain the physical and chemical
properties of various compounds in terms of their molecular structures.
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Back to Branches of Chemistry
Identify the branch of chemistry which would be associated with each of the following tasks.
1. creating analyzing new chemicals made from carbon-containing building blocks.
2. analyzing the composition of medicines and researching new combinations of compounds to use as drugs.
3. identifying enzymes and determining reaction mechanisms for biochemical reactions.
4. utilization of a computer to explain the physical and chemical properties of various compounds in terms of their molecular structures.
5. measuring the amount of energy released or absorbed in chemical processes.
6. studying and developing new materials to improve existing products or make new ones.
organic chemistry
analytical chemistry
biochemistry
theoretical chemistry
physical chemistry
inorganic chemistry
Scientific Method
The scientific method is a way to ask and answer scientific questions by making observations and doing experiments.
Scientists use the scientific method to search for cause and effect relationships in nature.
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Observations
Observations are made through the use of your senses. Your five senses are:
Touch Hearing
Smell Taste
Sight
Observations must be specific and accurate, not relative, so that they mean the same to everyone.
Incorrect – The burning bag smelled nasty.
Correct – The burning bag smelled similar to rotten eggs.
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Quantitative vs. Qualitative Observations
Observations may be qualitative or quantitative.
Qualitative Observations – factual descriptions that do not use numbers.
Example: Mr. Smith has brown hair.
Quantitative Observations – factual descriptions that use numbers.
Example: Mr. Smith is six feet tall.
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Inferences
Inferences are possible explanations based upon observations and previous knowledge.
Example: You leave the movie theater and see that the ground is wet so you infer that it rained.
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Classify each of the following statements as observations or inferences.
1. The bird feeder is empty.
2. The birds must have eaten all the seeds in the feeder.
3. The car has a flat tire.
4. The driver must have run over a nail.
observation
inference
observation
inference
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Steps in the Scientific Method
Step 1: Ask a Question
The scientific method starts when you ask a question about something that you observe.
Ask a Question
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Steps in the Scientific Method
Step 2: Gather Information
Information can be gathered in many ways.
Some examples of ways in which information could be gathered include:
Making observations
Conducting background research
Ask a Question
Gather Information
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Steps in the Scientific Method
Step 3: Formulate a hypothesis.
A hypothesis is a tentative explanation (educated guess) for an event.
Hypothesis are sometimes written as “if-then” statements.
For example, If I eat 2 gallons of ice cream, then I will get sick.
Ask a Question
Gather Information
Formulate a Hypothesis
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Evaluating Hypotheses
A good hypothesis is one that can be tested.
Evaluate each of the following hypotheses as to whether or not they can be tested.
1. If the polar ice caps begin to melt, the amount of salt in the ocean water will change.
2. Dogs use mind control on their owners to be taken for walks and car rides.
Can be tested
Cannot be tested Main Menu
Steps in the Scientific Method
Step 4: Conduct an Experiment
An experiment is a controlled procedure designed to test your hypothesis.
When you conduct an experiment, you will manipulate variables. Variables are factors that affect the outcome of an experiment.
It is important to manipulate only one variable at a time, so that you will be able to identify what is causing the outcome.
In many experiments, it is valuable to have a control, that is a standard for comparison.
Ask a Question
Gather Information
Formulate a Hypothesis
Conduct an Experiment
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Types of Variables
An independent variable is the variable that you control or change. In the ice cream example, the independent variable is the amount of ice cream I eat.
A dependent variable is the variable that you measure. In the ice cream example, the dependent variable is whether or not I get sick.
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Identifying the Parts of an Experiment
You are asked to study the effect of temperature on the volume of a balloon. The balloon’s size increases as it is warmed.
1. What is the independent variable?
2. What is the dependent variable?
3. What factor is held constant?
4. How would you construct a control?
the temperature
The amount of air in the balloon
the size of the balloon
Use an identical balloon kept at room temperature.Main Menu
Steps in the Scientific Method
Step 5: Record and Analyze Data
Once your experiment is complete, the results should be analyzed to determine if your data supports your hypothesis.
If your data does not support your hypothesis, you will need to revise or reject your hypothesis.
Ask a Question
Gather Information
Formulate a Hypothesis
Conduct an Experiment
Record and Analyze Data
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Steps in the Scientific Method
Step 6: Report Results
Before communicating the results of an experiment to others, you should repeat the experiment several times to make sure that the first results weren’t just an accident.
Ask a Question
Gather Information
Formulate a Hypothesis
Conduct an Experiment
Record and Analyze Data
Report Results
(Conclusion)
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Models
A model is a visual, verbal, and/or mathematical explanation of experimental data.
Scientists often create models to help them test hypothesis and/or make predictions.
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Uses of Models
Models help simulate behavior of larger or smaller objects.
Ex. Model airplane
Models help predict future events.
Ex. Computer model of a storm
Models help us visualize objects.
Ex. Architectural model
Models can be used to explain structure and process.
Ex. Molecular model
Models provide experiences that might be dangerous or unavailable.
Ex. Flight SimulatorMain Menu
Theory
A theory is an explanation that has been supported by many, many experiments. All theories are subject to new experimental data and can be modified.
Example: Atomic Theory
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Scientific Law
A scientific law is a concise statement that summarizes the results of a broad variety of observations and experiments and is generally accepted as true.
A law may be in words or in mathematical form.
Ex. E=mc2Main Menu
States of Matter
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Matter exists in many different forms, and it can be classified in many different ways.
One way that matter can be classified is according to its physical state.
The three most common states of matter are solids, liquids, and gases.
Scientists recognize a fourth state of matter called plasma, but it does not occur naturally on Earth except in the form of lightning bolts.
Properties Commonly Used to Describe Solids, Liquids and Gases
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Fluidity – the ability of a substance to flow and therefore conform to the outline of its container.
Compressibility – the ability of a substance to be pressed together or compacted, thereby reducing the volume of the substance without changing its mass.
Rigidity – the property of a substance that describes the inability of an object to change shape, inflexibility or stiffness of a substance.
Properties of Solids
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The particles in a solid:
• are packed very close together.• are held together with strong intermolecular
forces or bonds• vibrate slowly in place
Solids:• have a definite shape• maintain their shape. This means they are rigid.• have a definite volume.• are incompressible• are relatively dense
Properties of Liquids
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The particles in a liquid: • are close together with some
intermolecular forces.• are able to move (slide past each other), but
movement is limited by intermolecular forces.
Liquids:• do not have a definite shape. • have a definite volume.• flow and fill the bottom of a container. This
means they are not rigid.• Are difficult to compress because there a quite a
low of particles in a small volume.
Properties of Gases
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The particles in a gas: • are far apart• are free to move in all directions• Have very weak intermolecular forces of
attraction
Gases:• do not have a definite shape. • flow and expand to fill any container. • are easily compressed• are often low density as there are not many
particles in a large space.
Properties and Changes in Matter
•Matter can be described in many different ways.
•One way matter can be described is according to its chemical and physical properties.
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PhysicalProperties
Chemical Properties
Properties that can be observed or measured without causing change to the substance’s composition.
Properties that relate to a substance’s ability to undergo changes to its composition.
Example: Magnesium Ribbon is silvery-white and is very light.
Example:
Magnesium burns in air to produce magnesium oxide.
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Classify each of the following as either a chemical or physical property.
1. Water boils at 100ºC. Physical
2. Wood is flammable.Chemical
3. Aluminum has a low density.Physical
4. Iron rusts in a damp environment.Chemical
5. Gasoline burns in the presence of oxygen.Chemical Main
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EXTENSIVEINTENSIVEProperties that do NOT depend on the sample size.
Properties that DO depend on the sample size.
Examples:DensityMelting PointMalleability
Examples:MassVolume
Another way of separating kinds of physical properties is to think about whether or not the size of the sample would affect a particular property.
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Classify each of the following as either an intensive or an extensive physical property.
1. Boiling Point. Intensive
2. VolumeExtensive
3. DensityIntensive
4. MassExtensive
5. MalleabilityIntensive Main
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Physical Changes
• Changes that do not result in the production of a new substance are known as physical changes
• The chemical composition is not changed during a physical change.
• Examplesfolding paper
melting butterdissolving salt in water Main
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Chemical Changes
• Changes in which one or more substances are converted into different substances with different chemical and physical properties.
• Chemical changes are also called chemical reactions.
• ExamplesBurning PaperReacting Acid with water
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Indications of a Chemical Change
• Formation of a gas (bubbling)
• Change in energy Endothermic – energy is absorbed,
surroundings get cold
Exothermic – energy is released, surroundings get warm
• Production of a precipitate
• Change in color or odorMain Menu
Classify each of the following as either a chemical change or a physical change.
1. Crushing an aluminum canphysical
2. Silver tarnishingchemical
3. A metal chair rustschemical
4. Dissolving sugar in waterphysical
5. Water freezing and forming icephysical Main
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Law of Conservation of Mass
• During a chemical change, the amount of matter present before the reaction is equal to the amount of matter after the reaction.
• In ordinary chemical reactions, matter can change forms, but it cannot be created or destroyed.
• This is known as the Law of Conservation of Mass. Main
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Identifying Reactants and Products
• The reactants are the chemicals present before a chemical reaction.
• The products are the chemical that are present after a chemical reaction.
• Reactants → Products
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Identifying Reactants and Products
Examine the following chemical equation in which sodium metal and chlorine gas react to form solid sodium chloride.
2Na(s) + Cl2(g) → 2NaCl(s)
Identify the reactant(s).Sodium (Na) and Chlorine (Cl2)
Identify the product(s).Sodium Chloride (NaCl) Main
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Note: The (s) and (g) indicate the physical state of each element substance.
Identifying Reactants and Products
Examine the reverse reaction in which solid sodium chloride is decomposed to form sodium metal and chlorine gas.
2NaCl(s) → 2Na(s) + Cl2(g)
Identify the reactant(s).Sodium Chloride(NaCl)
Identify the product(s).Sodium (Na) and Chlorine (Cl2) Main
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Law of Conservation of Mass
According to the law of conservation of mass, the total mass of the reactants of a chemical reaction must be equal to the total mass of the products present after a chemical reaction.
If the mass of all of the reactants and products except one are known, the law of conservation of mass can be used to calculate the mass of the other substance.
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Law of Conservation of Mass
Hydrogen reacts with oxygen according to the following reaction to produce water.
2H2 + O2 2H2O
How many grams of water will be produced if 4.0 g of hydrogen reacts with 32.0 g of oxygen?4.0 g + 32.0 g = 36.0 g
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Law of Conservation of Mass
Use the illustration below to determine the amount of zinc produced.
The amount of zinc produced is 64 g + 192 g = 152 g + ? Ans. 104 g
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Energy
Energy is the capacity for doing work or supplying heat.
There are many different kinds of energy present in the universe: electrical, light, sound, heat, nuclear, solar, and chemical for example.
The SI unit for energy is the joule (J).
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Energy
Many forms of energy can be classified under two larger categories of energy.
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Potential energy is stored energy. It is energy due to position or composition.
Kinetic energy is the energy of motion. The kinetic energy of a substance depends on the mass and velocity of the substance.
Law of Conservation of Energy
The law of conservation of energy states that energy cannot be created nor destroyed. It can however, be converted from one form to another.
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Law of Conservation of Energy
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The nuclear energy produced when hydrogen nuclei fuse into helium nuclei in the sun’s core is converted to
solar energy in the form of electromagnetic radiation. This solar energy travels from the sun through the vacuum of space and reaches the earth. This solar energy is converted to
Law of Conservation of Energy
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chemical energy. Plants convert the solar energy into chemical energy in the form of carbon compounds (sugars) through the process of photosynthesis. Dead plants are compressed and over time are converted to hydrocarbons which contain high energy bonds. The chemical energy from the coal is converted to
electrical energy. The electrical energy can be used to power things like your television set. The electrical energy is converted to heat, light, and sound.
Endothermic vs. Exothermic Reactions
Endothermic Reaction
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Exothermic Reaction
Reaction Progress
R
PReaction Progress
R
P
There is an overall absorption of energy.
There is an overall release of energy.
CH4 + 2O2 CO2 + 2H2O + energy2NaCl + energy 2Na + Cl2
Classify each of the following as endothermic or exothermic.
1. The products have more potential energy than the reactantsendothermic
2. When two chemicals are mixed in a beaker, the beaker gets warm.exothermic
3. boiling waterendothermic
4. H2 + I2 + energy → 2HIendothermic Main
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Classifications of Matter
Matter is anything that has mass and volume
Matter can be classified in several different ways.
Two common ways to classify matter are uniformity and ability to be broken down into simpler substances.
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HeterogeneousHomogeneousHomogeneous materials are uniform throughout.
Heterogeneous materials are not uniform throughout.The individual components are often visible.Heterogeneous materials often settle upon standing.
Examples:elementscompoundssolutions alloys
Examples:tossed saladbowl of raisin bran
Homogeneous vs. Heterogeneous
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Classify each of the following as homogeneous or heterogeneous.
1. Crunchy peanut butterheterogeneous
2. Paintheterogeneous
3. Steelhomogeneous
4. 3% hydrogen peroxide solutionhomogeneous
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Elements• Elements are pure substances that are made of only one type of atom.
• Elements are homogeneous.
• Elements cannot be separated into simpler substances by ordinary chemical or physical means.
• The known elements are listed on the periodic table.
• Chemical symbols are used to represent the elements. Ex. C, H, N
Compounds• Compounds are pure substances that are made of more than one type of atom chemically combined.
• Compunds are homogeneous.
• The properties of a compound are different from those of the elements from which it is made.
• Compounds can be broken down into their elements by chemical means.
• The elements making up a compound are always combined in the same ratio.
• Chemical formulas are used to represent compounds. Ex. NaCl, C12H22O11, H2O, CO2
Mixtures• Mixtures are physical combinations of two or more kinds of matter, each of which retains its own identity and properties.
• Mixtures can be homogeneous or heterogeneous.
• Homogeneous mixtures are called solutions. Examples include alloys, salt water, pure air
• Mixtures can be separated into simpler substances by physical means. Ex. Distillation, filtration, chromatography.
• Different mixtures of the same substance can have different compositions.
Classify each of the following as elements, compounds or mixtures.
1. spaghetti saucemixture
2. table sugarcompound
3. river watermixture
4. nitrogen gaselement
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NO
Matter
Is it uniform throughout?
NO
NO
YES
YES
YES
Solution
Homogeneous
Does it have a variable composition?
Heterogeneous Mixture
Pure Substance
Can it be separated into simpler substances?
Element Compound
Introduction to the Periodic Table
The periodic table is a tool that organizes the known chemical elements according to trends in their chemical and physical properties Main
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Element Squares
Atomic Number
Chemical Symbol
Element Name
Atomic Mass
14
Si28.086
Silicon
The element squares on the periodic table provide important information about each element.
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Use your periodic table to complete the following table.
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Element Name
Chemical Symbol
Atomic Number
Atomic Mass
Hydrogen
Cu
9
H 1 1.008
Copper 29 63.546
Fluorine F 18.988
Solid, Liquid or Gas?
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Some periodic table allow determination of the phase of the elements under standard conditions by coloring the element symbol differently for each phase.
How does the periodic table in the classroom indicate whether a substance is a solid, liquid, or gas?
The chemical symbols for the solids are written in black. The chemical symbols for the gases are written in red.The chemical symbols for the liquids are written in blue.
Solid, Liquid or Gas?
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Are most of the elements solids, liquids or gases?Solids
Which elements exist as liquids at room temperature?
Bromine and Mercury
Which elements exist as gases at room temperature?Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Helium, Neon, Argon, Krypton, Xenon and Radon
Arrangement of the Periodic Table
The elements in the periodic table are arranged in order of increasing atomic number. Main
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Arrangement of the Periodic Table
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The columns of elements in the periodic table are called groups or families.
Elements with the same family have similar chemical properties.
How many groups of elements are there in the periodic table?18
Arrangement of the Periodic Table
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Each row of elements in the periodic table is called a period.
The elements within the same period are not alike in properties.
How many periods of elements are there in the periodic table?7
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Properties of Metals, Nonmetals and Metalloids
Metals are shiny, metallic, and good conductors of electricity.
Nonmetals are dull in appearance, brittle, and do not conduct electricity.
Metalloids tend to be brittle and semiconductors of electricity.. Main
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USE YOUR PERIODIC TABLE TO COMPLETE THE FOLLOWING TABLE TABLE.
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Element Name
Chemical Symbol
Group Number
Period Number
Solid, Liquid or
Gas?
Metal, Nonmetal or Metalloid?
Strontium
Ne
14 3
Sr 2 5 Solid MetalNeon 18 2 Gas Nonmetal
Silicon Si Solid Metalloid