Chemical World Year 9

Flashcards about chemical concepts for Year 9 students.

What is the origin of the word 'atom'?

Democritus named the tiniest particles of matter 'atomos', which means 'unable to be divided'.

What are the location, relative charge, and relative mass of protons, electrons, and neutrons?

Proton: Nucleus, +1, 1; Electron: Electron Shells, -1, 0; Neutron: Nucleus, 0, 1

What does the atomic number (Z) represent?

The atomic number (Z) is the number of protons in an atomic nucleus.

What does the mass number (A) represent?

The mass number (A) is the total number of protons and neutrons in an atomic nucleus.

How do you calculate the number of neutrons in an atom?

Number of neutrons = Mass number – Atomic number

How do you determine the number of electrons in an atom?

The number of electrons in an atom is the same as the atomic number.

What are isotopes?

Isotopes of an element are atoms with the same atomic number but with a different mass number due to a different number of neutrons.

How can elements be classified, and what are their properties?

Metals: shiny, malleable, ductile, conducts electricity, found on LHS and middle of periodic table; Non-metals: not malleable or ductile, doesn’t conduct electricity, found on RHS of periodic table; Metalloid: appearance and some physical properties of metals, behaves chemically like a non-metal, found at 'steps'.

How are elements classified on the periodic table based on the staircase line?

Elements on the left of the stairs are metals, elements on the right of the stairs are non-metals, and elements on the stairs are metalloids.

What are the different models of the atom in chronological order?

Solid Sphere Model (Dalton), Plum Pudding Model (Thomson), Nuclear Model (Rutherford), Planetary Model (Bohr), Quantum Model (Schrödinger)

What are the rules for electronic configuration?

Each shell can contain a maximum number of electrons, and lower energy shells fill before higher energy shells following 2,8,8,2 rule.

What is the maximum number of electrons each of the first four electron shells can contain?

Shell 1: 2 electrons, Shell 2: 8 electrons, Shell 3: 8 electrons, Shell 4: 2 electrons

What are the names of Group 1, Group 7, and Group 8 elements?

Alkali metals (Group 1), Halogens (Group 7), Noble gases (Group 8)

Why is an atom electrically neutral?

The atom doesn’t have an electrical charge because it has the same number of positive protons in the nucleus as there are negative electrons orbiting it.

What is the octet rule in relation to noble gases?

The Octet rule can also be thought of as attempting to gain the electronic configuration of the closest noble gas.

How are positive ions (cations) formed?

Metal atoms lose their outer electrons to be left with a full outer shell forming positive ions called CATIONS.

How are negative ions (anions) formed?

Non-metal atoms gain electrons to get a full outer shell forming negative ions called ANIONS.

What is a flame test, and what is it used for?

A flame test is a simple method used to determine the identity of a metal in a sample; different metals produce characteristic colors when heated in a flame.

How does ionic bonding occur?

Ionic Bonding: Metal and non-metal react. Metals form positive ions, Non-metals form negative ions. Opposite charges attract.

What is an ionic bond, and what type of structure do ionic compounds form?

An ionic bond is an electrostatic attraction between positive and negative ions and form crystalline lattice structures.

What information does a chemical formula provide?

Formulas tell you the type of atoms in a compound and the number of each atom. Numbers after brackets tell you how many times to multiply every atom inside the brackets.

How are ionic compounds named?

Monoatomic cations have the same name as the element, while monoatomic anions add 'ide' and 'ion' to the stem of the element; Oxoanions add 'ate' to the stem of the element that isn’t oxygen.

How is a covalent bond formed?

A covalent bond is formed when non-metal atoms share their valence shell electrons to become stable like noble gases.

How do isotopes of the same element differ?

Isotopes are atoms of the same element that differ in the number of neutrons in the nucleus.

What are the properties of alpha, beta, and gamma radiation?

Alpha is a heavy, positively charged particle with low penetrating power; Beta is a negatively charged particle with moderate penetrating power; Gamma is an electromagnetic wave with no charge and the highest penetrating power.

What is half-life?

The rate at which isotopes decay is described by its half-life—the time you would need to wait for half of the amount of the radioactive material to decay.