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HELUS Chemistry

Ch8: Chemistry

A ___ property is any characteristic of a substance that allows a substance to undergo a change that results in a new substance chemical
To observe some chemical properties, the original substance being observed must changeinto one or more ___ substances different
An example is iron’s chemical property of ___, which is only observed when iron turns to rust rusting
A chemical property can also describe how a substance ___ ___ change. An example of thiskind of chemical property is that helium does not burn does not
___ properties can be observed without changing the identity of the material beingobserved. Physical properties include malleability, conductivity, melting point, and color Physical
A ___ ___ is the change of one or more substances into other substances chemical change
Burning is a ___ change, and cannot be reversed chemical
One type of chemical change takes place when a ___ is decomposed into its elements. compound
A chemical change takes place when two or more ___ join to form a compound elements
___ ___ do change the properties of a substance, but not the identity of the substance Physical changes
___ is a process in which substances mix evenly with one another, and is a physical change that can be reversed. Dissolving
In all chemical reactions, the amount of ___ is the same before and after the change takes place. matter
In a chemical reaction, ___ between atoms break and new chemical bonds form, butthere are the same number and types of atoms before and after a chemical reaction bonds
The chemist Antoine Lavoisier conducted experiments that supported the law of___ of mass, which states that the total mass before a chemical reaction is thesame as the total mass after the reaction. conservation
___ are the starting materials in a chemical reaction Reactants
In chemical equations, the reactants are written on the ___ side of an arrow pointing to the right. left
If there are multiple reactants in a reaction, they are written with ___ signs separating them plus
___ are the new substances that are formed during a chemical reaction Products
Products in a ___ are separated from each other by plus signs. reaction
The products in a chemical reaction are written on the ___ side of the arrow right
Elements contain one type of ___. atom
A ___ is a neutral particle in which atoms share electrons. It can be a compound or an element. molecule
If the atoms in a molecule all have the same atomic number, the molecule is an ___ element
A ___ molecule is a molecule that contains two atoms diatomic
Molecules composed of two or more different atoms are ___ compounds
A ___ unit is the smallest whole-number ratio of the elements in an ionic or covalentcompound. formula
Two examples of formula units are ___ and H2O NaCl
A ___ ___ is an efficient way to represent what happens in a chemical reaction chemical equation
The chemical symbols for the ___ are separated by plus signs and written on the lefthand side of a horizontal arrow pointing to the right. reactants
The plus sign in a chemical equation can be read as “reacts with,” while the arrow can beread as “___.” produces
The chemical symbols for the ___ are separated by plus signs and written on the righthand side of a horizontal arrow pointing right. products
The chemical equation for the burning of charcoal, which is the reaction of carbon and___ to produce carbon dioxide, is written as C + O2 → CO2. oxygen
___ a chemical equation means writing the equation so that the same number of eachtype of atom exists on both sides of the arrow in the equation. Balancing
A ___ is the small number written to the right of a chemical symbol that tells how many atoms of an element are contained in one molecule of a substance subscript
___ are the full-sized numbers written in front of symbols and formulas. Acoefficient tells how many atoms, molecules, or formula units take part in a chemicalreaction. Coefficients
To balance a chemical equation, choose ___ for each reactant or product so that the same number of atoms is shown on each side of the equation. coefficients
You must balance each type of ___ separately, working through them one by one atom
For the decomposition of ___, the balanced equation is written as 2H2O → 2H2 + O2. water
Natural gas is made up mostly of the compound ___, whose chemical formula is CH4 methane
Methane reacts with oxygen in the air to produce ___ ___ and water. The balanced chemical equation for this reaction is CH4 + 2O2 → CO2 + 2H2O. carbon dioxide
When an element occurs in more than one product or reactant, balance the number ofatoms of that element ___. For example, in the methane reaction, you should count thenumber of oxygen atoms last. last
The balanced equation for the reaction of baking soda with ___ isNaHCO3 + HC2H3O2 → CO2 + H2O + NaC2H3O2. vinegar
The atoms within the ___ of an equation act as one unit. A subscript or coefficient multiplies the number of each type of atom in the parentheses parentheses
The rearrangement of atoms involves energy. The energy involved in many chemical reactions is ___. heat
Some chemical reactions can produce energy as light, with almost no ___ energy (or heat thermal
___ ___ is a term used for light that is produced at room temperature, or at a temperature lower than an incandescent bulb needs to produce light. Cold light
Light sticks and fireflies use chemical ___ that produce cold light. reactions
The law of conservation of ___ states that energy is neither created nor destroyed in chemical reactions. energy
The total amount of ___ before and after a chemical reaction stays the same energy
Energy changes from one ___ to another during a chemical reaction form
Molecules can store energy in ___ ___. In your body, digesting molecules of fat, protein, or carbohydrates transfers energy from chemical bonds in the molecules to yourcells. chemical bonds
An ___ process releases energy. The products of an exothermic process have lessenergy stored in their chemical bonds than the reactants exothermic
Burning is one example of an ___ ___. Products react with each other to produce reactants and heat exothermic process
An ___ process absorbs energy; the reactants have less energy than the products and are more stable than the products endothermic
In an ___ ___, energy has to be supplied to make the process happen endothermic process
The decomposition of water is an example of an endothermic reaction. Often, ___ is used to provide the energy needed to decompose water electricity
Created by: jnosik