Atomic Structure and the periodic table

What are atoms?

the smallest unit of an element, consisting of protons, neutrons, and electrons.

What is the atomic number and mass number?

Atomic number is the number of protons in the nucleus of an atom and mass number is the sum of protons and neutrons in an atom's nucleus.

What are the masses and charges of the subatomic particles?

Electron = -1 Mass = very small 1/2000

Neutron = 0 Mass = 1

Protons = +1 Mass = 1

What is an element?

An element is a substance made of only one type of atom.

What are isotopes?

Isotopes are atoms of the same element with different numbers of neutrons, leading to different mass numbers.

What is relative atomic mass?

Relative atomic mass is the weighted average mass of an element's isotopes, considering their abundance.

What is a Compound, mixture and molecule?

A compound is a substance formed when two or more different elements chemically bond.

A mixture is a combination of two or more substances where each retains its individual properties.

A molecule is a group of atoms bonded together; it can be an element or a compound.

What is the law of conservation of mass?

The law states that matter is neither created nor destroyed in a chemical reaction.

What is filtration?

Filtration is a process that separates insoluble solids from liquids using filter paper.

What is crystallisation?

Crystallisation is a method to separate a solid that has dissolved in a liquid by evaporating the solvent, leaving crystals of the solute.

Define Solute, solvent and solution

A solute is the substance that gets dissolved, a solvent is the substance that does the dissolving, and a solution is the homogeneous mixture formed when the solute is dissolved in the solvent

How do you calculate the Relative Atomic Mass?

multiply the mass number of each isotope by its relative percentage abundance, then add these values together and divide the sum by 100

What is simple distillation and fractional distillation?

Simple distillation is a process used to separate liquids with different boiling points.

Fractional distillation is used to separate mixtures of liquids with closer boiling points.

Who proposed the idea of indivisible particles?

Democritus proposed that matter is made of indivisible particles called atoms.

What was Dalton's model of the atom?

Dalton's model suggested that atoms are solid spheres; each element has its own type of atom.

What did Thomson propose about the atom?

Thomson proposed the "plum pudding" model, where atoms are spheres of positive charge with embedded electrons.

What did Rutherford's experiment reveal?

Rutherford's gold foil experiment revealed that atoms have a dense nucleus with electrons orbiting around it.

What is Bohr's model of the atom?

Bohr's model proposed that electrons orbit the nucleus in fixed shells.

What is the modern model of the atom?

The modern model suggests that electrons exist in probability clouds around the nucleus.

What are electron shells?

Electron shells are energy levels around the nucleus where electrons are found.

How many electrons can each shell hold?

First shell: 2 electrons; Second shell: 8 electrons; Third shell: 8 electrons.

What are valence electrons?

Valence electrons are electrons in the outermost shell; they determine chemical properties.

How do you figure out how many shells a element needs?

By looking at the period number row group e.g Carbon is in the second row which means it has 2 shells

How do you figure out how many Electrons on the outermost shells a element has?

By looking at the group the element is in. E.g Oxygen is in group six which means it has 6 electrons on the outermost shell.

Who arranged elements by atomic mass?

Dmitri Mendeleev arranged elements by atomic mass and properties.

How are elements arranged in the modern periodic table?

Elements are arranged by atomic number; elements with similar properties are in columns (groups).

What is the periodic law?

The periodic law states that properties of elements are a periodic function of their atomic numbers.

What defines a metal and a non-metal?

Metals lose electrons to form cations (this makes them form positive ions) ; non-metals gain or share electrons to form anions or covalent bonds (this makes them formo negative ions)

List three physical properties of metals versus non-metals.

• Metals: shiny, malleable, good conductors.

• Non-metals: dull, brittle, poor conductors.

Describe typical chemical behavior of metal oxides vs non-metal oxides.

Metal oxides are basic and often alkaline; non-metal oxides are acidic.

How does reactivity vary for metals and non-metals within a group?

Metal reactivity increases down a group; non-metal reactivity increases up a group.

List three physical properties common to transition metals.

They generally have high melting/boiling points, are dense, strong, and hard, and are excellent heat and electricity conductors

Why are transition metals good catalysts?

Because of their ability to adopt multiple oxidation states and form complexes, they facilitate reactions without being consumed

What is the definition of a catalyst?

A substance that can speed up a chemical reaction without being used up

What are the properties of alkali metals?

Alkali metals are soft, have low melting points and densities, and react vigorously with water to form alkaline hydroxides and hydrogen gas.

How does reactivity change in alkali metals?

Reactivity increases down the group. (outer electron is more easily lost)

What are group 1, 0 and 7 called?

1 = Alkali

0 = Noble gasses

7 = Halogens

What are the properties of halogens?

Halogens are non-metals with seven electrons in their outer shell, form salts when combined with metals, and have reactivity that decreases down the group.

Halogens trends?

As you go down less reactive, poisonous, its harder to gain an extra electron because the outer shells further from the nucleus, have higher melting and boiling points, they become darker in colour since they are coloured vapours.

What are the properties of noble gases?

Noble gases are inert, colorless, odorless, and tasteless, with full outer electron shells. and density increases.