Atomic Structure and the Periodic Table C1 Flashcards
What are all substances made of?
All substances are made of atoms.
How small are atoms?
Atoms are so tiny that a 50p piece contains about 77,400,000,000,000,000,000 atoms.
What do atoms contain?
Atoms contain protons, neutrons, and electrons.
What is the radius of an atom?
Atoms have a radius of about 0.1 nanometres.
What is located in the middle of the atom?
The nucleus is in the middle of the atom.
What particles are found in the nucleus?
The nucleus contains protons and neutrons.
What is the charge of the nucleus?
The nucleus has a positive charge because of the protons.
What is the relative mass of protons and neutrons?
Protons are heavy and positively charged; neutrons are heavy and neutral.
What is the charge of electrons?
Electrons are negatively charged.
How does the number of protons relate to the number of electrons in an atom?
The number of protons equals the number of electrons.
What determines the size of the atom?
The volume of the electron orbits determines the size of the atom.
How do you find the number of neutrons?
To get the number of neutrons, subtract the atomic number from the mass number.
What is the atomic number?
The atomic number tells you how many protons there are.
What is an ion?
An ion is an atom or group of atoms that has lost or gained electrons.
What is the nuclear symbol of an atom?
The nuclear symbol tells you its atomic (proton) number and mass number.
What is the atomic number and mass number of gallium?
An atom of gallium has an atomic number of 31 and a mass number of 70.
What is the nuclear symbol for sodium?
The nuclear symbol for sodium is Na with atomic number 11 and mass number 23.
What is the significance of understanding atomic structure?
Grasping the basic facts of atomic structure is crucial for understanding the rest of chemistry.
What are compounds?
Compounds are substances formed from two or more elements, with atoms in fixed proportions held together by chemical bonds.
How do atoms join to form compounds?
Atoms combine with other atoms when elements react to form compounds.
What is involved in making chemical bonds?
Making bonds involves atoms giving away, taking, or sharing electrons; the nuclei of the atoms aren’t affected.
How can original elements of a compound be separated?
It is usually difficult to separate the original elements of a compound; a chemical reaction is needed to do this.
What is ionic bonding?
Ionic bonding occurs when a compound formed from a metal and a non-metal consists of ions, where metal atoms lose electrons to form positive ions and non-metal atoms gain electrons to form negative ions.
What are examples of compounds bonded ionically?
Examples include sodium chloride, magnesium oxide, and calcium oxide.
What is covalent bonding?
Covalent bonding occurs in compounds formed from non-metals, where each atom shares an electron with another atom.
What are examples of compounds bonded covalently?
Examples include hydrogen chloride gas, carbon monoxide, and water.
How do the properties of a compound compare to the original elements?
The properties of a compound are usually totally different from the properties of the original elements.
What is the formula for carbon dioxide?
The formula for carbon dioxide is CO2.
What is the formula for ammonia?
The formula for ammonia is NH3.
What is the formula for water?
The formula for water is H2O.
What does a formula represent in a compound?
Formulas are made up of elemental symbols in the same proportions that the elements can be found in the compound.
What is the formula for sulfuric acid?
The formula for sulfuric acid is H2SO4.
What is the formula for hydrochloric acid?
The formula for hydrochloric acid is HCl.
What is the formula for sodium chloride?
The formula for sodium chloride is NaCl.
What is the formula for calcium chloride?
The formula for calcium chloride is CaCl2.
What is the formula for sodium carbonate?
The formula for sodium carbonate is Na2CO3.
What is the formula for iron sulfide?
The formula for iron sulfide is FeS.
What elements are in the compound Al2(SO4)3?
The elements are aluminum (Al) and sulfur (S), along with oxygen (O).
What happens during a chemical reaction?
During a chemical reaction, at least one new substance is made, and you can usually measure a change in energy.
What are chemical equations fundamental to?
Chemical equations are fundamental to chemistry.
What do chemical equations show?
Chemical changes are shown using chemical equations.
What are the reactants in a chemical equation?
The molecules on the left-hand side of the equation are called the reactants.
What is an example of a word equation?
Methane burns in oxygen giving carbon dioxide and water.
Example: methane + oxygen → carbon dioxide + water
What do symbol equations show?
Symbol equations show the symbols or formulas of the reactants and products.
What must be true for a balanced chemical equation?
There must always be the same number of atoms on both sides.
How do you balance a chemical equation?
You balance the equation by putting numbers in front of the formulas where needed.
What is an example of a symbol equation?
H₂SO₄ + NaOH → Na₂SO₄ + H₂O
Example: 2Mg + O₂ → 2MgO
What should you do if you find an unbalanced element?
Pencil in a number to try and sort it out.
What happens if balancing creates another imbalance?
If it creates another imbalance, pencil in another number and see where that gets you.
What is the right-hand side of a chemical equation called?
The molecules on the right-hand side are called the products.
What is the goal of revision in balancing equations?
Revision is all about getting the balance right.
What is the key to mastering balancing equations?
Balancing equations is all about practice.
What are mixtures in chemistry?
Mixtures in chemistry consist of lots of separate things all mixed together.
How can the parts of a mixture be separated?
The parts of a mixture can be separated using physical methods such as filtration, crystallization, simple distillation, fractional distillation, and chromatography.
What is an example of a mixture?
Air is a mixture of gases, mainly nitrogen, oxygen, carbon dioxide, and argon.
What is crude oil a mixture of?
Crude oil is a mixture of different length hydrocarbon molecules.
How do the properties of a mixture relate to its components?
The properties of a mixture are just a combination of the properties of the separate parts; the chemical properties of a substance aren’t affected by being part of a mixture.
For example, a mixture of iron powder and sulfur powder will show the properties of both iron and sulfur.
What is paper chromatography?
Paper chromatography is a method used to separate substances in a mixture, such as different dyes in an ink.
What should you use to draw the line on filter paper for chromatography?
You should use a pencil to draw the line on filter paper because pencil marks are insoluble and won’t dissolve in the solvent.
What happens when the solvent moves up the paper in chromatography?
The solvent seeps up the paper, carrying the ink with it, and each different dye will move up the paper at a different rate, forming spots.
What is a chromatogram?
The end result of chromatography is a pattern of spots called a chromatogram.
What is the solvent front in chromatography?
The solvent front is the point the solvent has reached as it moves up the paper.
Why shouldn’t you use a pen to draw a line on the filter paper for paper chromatography?
You shouldn’t use a pen because pen marks are soluble and can dissolve in the solvent, affecting the results.
What are some real-life applications of chromatography?
Chromatography is used to test athletes’ urine samples for performance-enhancing drugs and to test unknown substances at crime scenes.
What is filtration used for?
Filtration is used to separate insoluble solids from liquids.
What are two methods to separate soluble solids from solutions?
The two methods are evaporation and crystallisation.
What happens during evaporation?
The solvent evaporates, concentrating the solution until crystals form.
What is the first step in crystallisation?
Pour the solution into an evaporating dish and gently heat it.
What should you do when you see crystals start to form during crystallisation?
Remove the dish from heat and leave the solution to cool.
How can you separate rock salt?
Filter the mixture to separate sand (insoluble) from salt (soluble).
What is a vital difference between salt and sand?
Salt dissolves in water, while sand does not.
What can be used instead of a Bunsen burner for heating?
You could use a water bath or an electric heater.
How can you produce pure crystals of copper sulfate?
Use crystallisation to separate it from an aqueous solution.