Periodic Table Flashcards
What is an atom?
The smallest part of an element that can exist.
Atoms are the basic building blocks of matter.
Describe Dalton’s model of the atom.
Atoms as solid spheres that cannot be divided into smaller parts.
Dalton proposed that atoms are indivisible and maintain their identity in chemical reactions.
What is an element?
A substance made of one type of atom.
E.g., oxygen = O2, iron = Fe.
Elements are pure substances that cannot be broken down into simpler substances.
What is a molecule?
A particle made of two or more atoms joined together.
E.g., oxygen = O3, water = H2O.
Molecules can consist of the same or different types of atoms.
What is a diatomic molecule?
A molecule that consists of two atoms, often the same.
E.g., O2, Cl2.
Diatomic molecules are important in various chemical reactions.
What is a chemical symbol?
A one or two universal letter code of each element.
Chemical symbols are used to represent elements in chemical formulas.
Where are chemical symbols of elements found?
In the periodic table.
The periodic table organizes elements based on their properties.
What is a compound?
A substance made of more than one type of atom chemically joined together.
E.g., water = H2O, carbon dioxide = CO2.
Compounds have different properties than the elements that make them up.
What is a chemical formula?
A formula that shows the number and type of atoms present in a molecule.
Chemical formulas provide essential information about the composition of compounds.
What do the compound endings ‘ide’ and ‘ate’ mean?
1) ide - a compound of only the named substances.
2) ate - a compound of the named substances and oxygen.
These endings help identify the composition of chemical compounds.
What is a physical change?
Changes of state as no new substances are made.
Physical changes include changes in state, shape, or size without altering the substance’s composition.
What is a chemical change (Chemical reaction)?
When atoms rearrange to make new substances.
Chemical changes involve breaking and forming bonds between atoms.
Where do we find metals in the periodic table?
On the left.
Metals are typically located on the left side of the periodic table and are characterized by specific physical properties.
Where do we find non-metals on the periodic table?
On the right.
Non-metals are found on the right side of the periodic table and have distinct properties compared to metals.
Who designed the modern periodic table?
Mendeleev.
Mendeleev organized elements based on atomic mass and properties, leading to the development of the periodic table.
What are the groups in the periodic table?
Columns.
Groups contain elements with similar chemical properties.
What are the rows called in the periodic table?
Periods.
Periods indicate the energy levels of the electrons in the atoms.
What are the physical properties of most metals?
- Good conductors of electricity
- Good conductors of heat
- Shiny
- High density (heavy for its size)
- Malleable (can be hammered)
- Sonorous (makes a ringing sound when hit)
- Ductile (can be pulled into wires)
- High melting points (except mercury)
- Hard
Metals exhibit these characteristics due to their atomic structure.
What are the physical properties of non-metals?
- Poor conductors of electricity
- Poor conductors of heat
- Dull
- Low density (light for its size)
- Brittle (breaks easily)
- Non-sonorous (no ringing sound when hit)
- Low melting points
Non-metals have distinct properties that differentiate them from metals.
What is the formula to calculate the relative atomic mass of an element with isotopes?
((isotope 1 mass x abundance) + (isotope 2 mass x abundance)) ÷ 100
How do you calculate the relative atomic mass of carbon with isotopes carbon-14 and carbon-12?
For carbon: ((14 × 20) + (12 × 80)) ÷ 100 = 12.4
What do electrons occupy in an atom?
Electrons occupy the lowest available energy levels (the shells closest to the central nucleus).
What does the electronic structure of an atom indicate?
The electronic structure tells you how many electrons are in each shell.
What is the electronic structure of sodium?
2, 8, 1
Sodium has 2 electrons in shell 1, 8 in shell 2, and 1 in shell 3.
What are atoms?
Atoms make up all substances and are the smallest part of an element that can exist
What do chemical symbols represent?
Chemical symbols represent an atom of an element; e.g., Na represents an atom of sodium
How are compounds formed?
Compounds are formed from elements by chemical reactions
What do compounds contain?
Compounds contain two or more elements chemically combined in fixed proportions
Give an example of a compound and its composition.
HCl is a compound containing 1 atom of hydrogen and 1 of chlorine per molecule
How can compounds be separated into elements?
Compounds can only be separated into elements by chemical reactions
What is a mixture?
A mixture consists of two or more elements or compounds not chemically combined together
What happens to the chemical properties of substances in a mixture?
The chemical properties of each substance in the mixture are unchanged
How can mixtures be separated?
Mixtures can be separated by:
* filtration
* crystallisation
* simple distillation
* fractional distillation
* chromatography
What distinguishes the separation of mixtures from compounds?
Separation of mixtures involves physical processes, so no new substances are made
What was the first model of the atom?
Atoms were thought to be tiny spheres that could not be divided
What is the plum pudding model?
The plum pudding model describes the atom as a ball of positive charge with negative electrons embedded in it
What conclusion was drawn from the alpha particle scattering experiment?
The mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged
Describe the alpha particle scattering experiment.
A beam of alpha particles was aimed at very thin gold foil; some particles were deflected at different angles and some came straight back
What did the scattering experiment reveal about the nucleus?
Positively charged alpha particles were being repelled and deflected by a small concentration of positive charge in the atom (nucleus)
What did Neil Bohr suggest about electrons?
Neil Bohr suggested that electrons orbit the nucleus at specific distances
True or False: A mixture can only be separated by chemical reactions.
False
Fill in the blank: Compounds can only be separated into elements by _______.
chemical reactions
What is the positive charge of any nucleus subdivided into?
Whole number of smaller particles called protons
Who provided the evidence for the existence of neutrons?
James Chadwick
What is the atomic number?
The number of protons in an atom of an element
Do all atoms of a particular element have the same number of protons?
Yes
What is the relative charge of a proton?
+1
What is the relative charge of a neutron?
0
What is the relative charge of an electron?
-1
What must be true for an atom to have an overall charge of 0?
Number of protons = number of electrons
What is the approximate radius of an atom?
About 0.1 nm
How does the radius of a nucleus compare to that of an atom?
Less than 1/10,000 of that of the atom
What is the mass number?
The sum of the protons and neutrons in an atom
What are isotopes?
Atoms of the same element with different numbers of neutrons
What does the mass number indicate in the periodic table?
Total number of protons and neutrons
If an atom has a mass number of 19 and 9 protons, how many neutrons does it have?
10 neutrons
What is relative atomic mass?
An average value that takes account of the abundance of the isotopes of the element
What does the atomic number indicate?
The number of protons in an atom
Fill in the blank: Atoms are very small, with a radius of about _______.
0.1 nm
True or False: An electron has a relative mass of 1.
False
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of an electron?
Very small
